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Entire Hierarchy

A: Transportation
    Aa: Multimodal transportation
    Ab: Intermodal transportation
    Ac: Dual mode transportation systems
    Ae: Transportation modes
        Aea: Air transportation
            Aeac: Air taxi service
            Aeah: Helicopter transportation
            Aeap: Private flying
            Aeas: Commercial space transportation
        Aeg: Ground transportation
            Aegh: Highway transportation
                Aeghb: Bus transportation
                Aeght: Trucking
                    Aeghtp: Private trucking
                    Aeghtt: Tank trucking
            Aegk: Railroad transportation
                Aegkm: Monorail transportation
                Aegkt: High speed ground transportation
            Aegp: Pipeline transportation
        Aes: Water transportation
            Aesb: Shipping
                Aesbb: Ocean shipping
                    Aesbba: Liner shipping
                    Aesbbd: Tanker shipping
                    Aesbbe: Tramp shipping
                    Aesbbh: Heavy lift shipping
                Aesbc: Coastwise shipping
                Aesbe: Short sea shipping
            Aesf: Ferry service
                Aesfr: Roll on roll off shipping
            Aesi: Inland water transportation
        Aet: Public transit
            Aetb: Bus transit
                Aetbj: Jitney service
                Aetbr: Bus rapid transit
            Aetr: Rail transit
                Aetrc: Railroad commuter service
                Aetrd: Rapid transit
                Aetrh: Light rail transit
            Aett: Paratransit services
                Aettb: Taxi services
                Aettd: Demand responsive transportation
            Aetw: Marine transit
        Aex: Nonmotorized transportation
            Aexb: Bicycling
            Aexw: Walking
    Af: Transportation by environment
        Afc: International transportation
        Afd: Domestic transportation
        Afe: Intercity transportation
        Aff: Interstate transportation
        Afg: Regional transportation
        Afj: Local transportation
        Afm: Rural transportation
            Afma: Rural transit
        Afn: Urban transportation
            Afna: Urban transit
        Afs: Emergency transportation
        Aft: Campus transportation
        Afw: Airport ground transportation
        Afy: Intra airport transportation
            Afyj: Intra airport transit
    Aj: Transportation by load
        Ajf: Freight transportation
        Ajp: Passenger transportation
    Am: Transportation by ownership
        Amc: Commercial transportation
        Amg: Government transportation
        Amm: Military transportation
        Amp: Private transportation
B: Transportation operations
    Bb: Freight and passenger services
        Bbb: Freight service
            Bbba: Intermodal services
                Bbbac: Containerization
                    Bbbacc: Container on flat car
                    Bbbacd: Doublestack service
                Bbbad: Piggyback transportation
                    Bbbadt: Trailer on flat car
                Bbbaf: Air truck transportation
                Bbbam: Rail marine interface
            Bbbb: Unitized cargo
            Bbbc: Air cargo
        Bbc: Passenger service
            Bbca: Commuter service
        Bbd: Vehicle passenger service
            Bbda: Auto on train
        Bbe: Package and mail service
            Bbec: Courier service
                Bbeca: Air courier service
            Bbee: Express service
            Bbem: Postal service
                Bbema: Air mail service
            Bbep: Package service
        Bbf: Service by length of haul
            Bbfg: Haul distance
            Bbfj: Line haul
            Bbfk: Short haul
                Bbfks: Shuttle service
            Bbfm: Pickup and delivery service
                Bbfma: Delivery service
            Bbfn: Feeder services
            Bbfr: Drayage
            Bbfu: Urban goods movement
        Bbg: Charter operations
            Bbgc: Chartering
                Bbgca: Air charter service
            Bbgp: Charter parties
            Bbgy: Charters
        Bbh: Routes and routing
            Bbhe: Routes
                Bbhea: Hub and spoke systems
                    Bbhead: Hubs
                Bbheb: Bus routes
                Bbhec: Fixed routes
                Bbhed: Trade routes
                Bbhef: Air routes
                Bbhek: Land bridge
                    Bbhekd: Minibridge
                    Bbhekm: Microbridge
                Bbhet: Truck routes
            Bbhr: Routing
                Bbhrd: Weather routing
                Bbhrt: Time windows
            Bbht: Door to door service
        Bbj: Schedules and scheduling
            Bbjf: Schedules
                Bbjft: Timetables
            Bbjh: Scheduling
            Bbjk: Schedule maintenance
                Bbjkm: On time performance
            Bbjp: Service time
            Bbjr: Layover time
            Bbjs: Dwell time
            Bbjt: Code sharing
            Bbju: Interlining
        Bbk: Rates, fares and tolls
            Bbkb: Rates
                Bbkbc: Contract rates
                Bbkbh: Charter rates
                Bbkbt: Tariffs
                Bbkbu: Rate making
            Bbkf: Fares
                Bbkfb: Peak fares
                Bbkfd: Distance based fares
                Bbkfh: Zone fares
                Bbkfk: Discount fares
                Bbkfm: Free fares
            Bbkt: Tolls
                Bbkts: Shadow tolls
                Bbktv: Variable tolls
            Bbkx: Rate, fare and toll collection
                Bbkxb: Freight billing
                Bbkxf: Fare collection
                Bbkxs: Toll collection
            Bbky: Fare and toll prepayment
                Bbkyc: Fare prepayment
                Bbkyp: Passes (Transportation)
                Bbkyt: Tokens
                Bbkyu: Ticketing
                    Bbkyut: Tickets
        Bbp: Reservations
            Bbps: Reservation systems
                Bbpsc: Computer reservation systems
                Bbpsk: Overbooking
        Bbq: In transit passenger services
            Bbqm: Inflight entertainment
            Bbqp: Food service
                Bbqpd: Dining car service
        Bbr: Quality of service
            Bbrm: Level of service
        Bbs: Ride quality
            Bbsa: Passenger comfort
        Bbt: Service discontinuance
        Bby: Freight documents
            Bbyb: Bills of lading
            Bbyf: Freight bills
            Bbyw: Waybills
                Bbyws: Waybill samples
    Bd: Freight and passenger handling
        Bdb: Freight handling
            Bdbb: Cargo handling
                Bdbbc: Bulk cargo handling
                    Bdbbck: Liquid cargo handling
            Bdbc: Container handling
            Bdbe: Accessorial services
                Bdbef: Fabrication
                Bdbet: Transit privileges
            Bdbf: Protective services
            Bdbp: Intermodal transfer
                Bdbpb: Offshore transfer
                    Bdbpbm: Lighterage
                Bdbpd: On dock transfer
            Bdbw: Load shifting
        Bdk: Passenger handling
            Bdkb: Baggage
                Bdkbh: Baggage handling
                Bdkbs: Baggage screening
            Bdkd: Boarding and alighting
                Bdkda: Alighting
                Bdkdb: Boarding
            Bdke: Automated checkin
            Bdks: Passenger screening
            Bdkt: Transfers
            Bdku: Transfer points
    Bf: Freight and passenger traffic
        Bfb: Freight traffic
            Bfbe: Container traffic
            Bfbg: Back haul
            Bfbj: Traffic loads
                Bfbja: Carloadings
                Bfbjb: Less than carload traffic
                Bfbjm: Less than truckload traffic
            Bfbm: Freight traffic measurement
                Bfbme: Empty car miles
                Bfbmt: Tonnage
                    Bfbmtb: Tonnage ratings
                Bfbmu: Ton miles
        Bfh: Passenger traffic
            Bfhm: Passenger traffic measurement
                Bfhmb: Passenger miles
                    Bfhmba: Passenger volume
                Bfhmr: Ridership
                Bfhmt: City pairs
    Bh: Commodities
        Bha: Commodity flow
        Bhc: Commodity classification
        Bhd: Commodity density
        Bhg: Commodity groups
            Bhgb: Bulk cargo
                Bhgbd: Dry bulk cargo
                Bhgbm: Liquid bulk cargo
            Bhgd: Hazardous materials
                Bhgdd: Hazardous wastes
                Bhgdr: Radioactive materials
                Bhgdw: Radioactive wastes
            Bhgf: Food
                Bhgfp: Processed foods
                Bhgfs: Seafood
            Bhgg: Beverages
            Bhgp: Perishables
            Bhgr: Refrigerated cargo
                Bhgrc: Chilled cargo
                Bhgrf: Frozen cargo
            Bhgw: Waste products
        Bhk: Commodities by type
            Bhkb: Agricultural products
                Bhkba: Crops
                Bhkbb: Farm produce
                    Bhkbba: Fruits and vegetables
                        Bhkbbab: Vegetables
                        Bhkbbaf: Fruits
                            Bhkbbafc: Containerized fruit
                    Bhkbbg: Legumes
                        Bhkbbgs: Soybeans
                Bhkbc: Livestock
                    Bhkbcm: Meat
                Bhkbd: Dairy products
                Bhkbe: Grain
                    Bhkbew: Wheat
                Bhkbs: Sugar
                Bhkbw: Feeding stuffs
            Bhkc: Forest products
                Bhkcm: Wood products
                Bhkcp: Paper products
            Bhkf: Mines and mineral products
                Bhkfb: Ores
                    Bhkfbi: Iron ores
                Bhkfc: Coal
                    Bhkfcs: Coal slurry
                Bhkfp: Petroleum
                    Bhkfpp: Petroleum products
            Bhkg: Fertilizers
            Bhkh: Manufactures
                Bhkhc: Chemicals
                Bhkht: Textiles
                    Bhkhtc: Cotton
    Bk: Travel and shipment characteristics
        Bkc: Carrier selection
        Bkj: Trip length
        Bkm: Mode choice
            Bkmb: Automobile ownership
        Bkn: Travel time
            Bknd: Departure time
        Bkq: Access
            Bkqf: Accessibility
            Bkqh: Distance
        Bkr: Route choice
            Bkrb: Itinerary
        Bks: Travel surveys
            Bksa: Origin and destination
                Bksam: Trip matrices
                Bksat: Trip tables
        Bkv: Vehicle occupancy
            Bkvs: Single occupant vehicles
    Bm: Travel
        Bmb: Travel by vehicle type
            Bmbb: Automobile travel
            Bmbc: Motorcycling
            Bmbd: Bicycle travel
                Bmbdd: Bicycle commuting
            Bmbh: Bus travel
        Bmc: Travel by mode
            Bmca: Air travel
            Bmcd: Highway travel
            Bmcr: Railroad travel
            Bmcs: Ocean travel
        Bmf: Travel by area
            Bmfj: International travel
            Bmfk: Intercity travel
            Bmfr: Rural travel
            Bmfu: Urban travel
        Bmk: Travel demand
            Bmkb: Traffic estimation
                Bmkbb: Trip generation
                Bmkbe: Trip distribution
                    Bmkbeg: Gravity models
                    Bmkbej: Interzonal trips
                    Bmkbem: Opportunity models
                Bmkbg: Modal split
                    Bmkbgb: Modal diversion
                    Bmkbgh: Modal shift
                Bmkbt: Traffic forecasting
            Bmkh: Trip purpose
                Bmkha: Airport access
                Bmkhb: Business trips
                Bmkhe: Emergency trips
                Bmkhm: Medical trips
                Bmkhq: Recreational trips
                    Bmkhqc: Camping
                Bmkhs: Shopping trips
                Bmkht: School trips
                Bmkhu: Tourism
                    Bmkhue: Ecotourism
                Bmkhw: Work trips
                    Bmkhwd: Deadheading
        Bmm: Travel behavior
            Bmmc: Trip chaining
            Bmmd: Travel costs
            Bmme: Travel diaries
            Bmmt: Radial travel
            Bmmu: Travel patterns
            Bmmw: Activity choices
            Bmmy: Time management
        Bmn: Commuting
            Bmnb: Reverse commuting
            Bmnd: Telecommuting
            Bmne: Employer sponsored transportation
            Bmnk: Kiss and ride
            Bmnr: Bike and ride
        Bmr: Ridesharing
            Bmrb: Buspools
            Bmrc: Carpools
                Bmrcc: Casual carpooling
            Bmrv: Vanpools
        Bms: Car sharing
    Bn: Shipments
        Bna: Air shipments
        Bnb: Small shipments
        Bnd: Military shipments
        Bnk: Shipper demand
        Bnn: Handling and storage
            Bnnc: Demurrage
            Bnnd: Detention
        Bnq: Freight claims
            Bnqj: Loss and damage claims
                Bnqjn: Overcharge claims
                Bnqju: Undercharge claims
    Bq: Transportation facility operations
        Bqa: Airport operations
            Bqaa: Airside operations
            Bqam: Landside operations (Airports)
                Bqams: Slot allocation
            Bqar: Ground handling
            Bqas: Concessions
            Bqat: Fixed base operations
            Bqau: Airport capacity
        Bqd: Highway operations
            Bqdc: Highway capacity
                Bqdcd: Design capacity
                Bqdcr: Capacity restraint
            Bqdo: Freeway operations
        Bqr: Railroad facility operations
            Bqrg: Gateways
            Bqrt: Trackage rights
            Bqry: Yard operations
        Bqt: Terminal operations
        Bqu: Station operations
        Bqw: Waterway facility operations
            Bqwb: Port operations
                Bqwbb: Berth utilization
                Bqwbc: Port capacity
                Bqwbm: Landside operations (Ports)
                    Bqwbmc: Landside capacity
            Bqwc: Canal operations
                Bqwct: Canal transit
                    Bqwctm: Canal lock operations
            Bqwd: Drydock operations
    Br: Vehicle operations
        Bra: Fleet management
            Brac: Vehicle classification
            Brad: Dispatching
            Brag: Loading and unloading
                Bragb: Blocking
                Bragc: Bracing
                Bragk: Lashing
                Bragm: Oversize loads
                Brago: Overweight loads
            Brah: Stowage
            Bram: Temperature control
                Bramb: Heating
                Bramr: Refrigeration
            Bran: Vehicle marking
                Brank: Labeling
                Branp: Placarding
            Bras: Vehicle capacity
        Brc: Aircraft operations
            Brcb: Arrivals and departures
            Brcc: Cockpit resource management
            Brcd: Crew resource management
            Brcf: Flight plans
        Brd: Motor vehicle operations
            Brdd: Parking
                Brdda: Parking duration
                Brddb: Parking turnover rate
                Brddd: Parking demand
                Brddf: Fringe parking
                Brddm: Off street parking
                    Brddms: Shared parking
                Brddn: On street parking
                    Brddna: Angle parking
                    Brddnc: Curb side parking
                    Brddnp: Permit parking
                Brddp: Pay parking
                    Brddpf: Parking fees
                    Brddpr: Parking meters
                Brddq: No parking
                Brddt: Airport parking
                Brddv: Campus parking
                Brddx: Bicycle parking
        Brr: Railroad vehicle operations
            Brra: Train operations
                Brram: Train makeup
                    Brrams: Switching
                        Brramsf: Flat switching
                        Brramsg: Gravity switching
                    Brramt: Train consist
                Brrat: Special train consists
                    Brratp: Push pull trains
                    Brratr: Run through trains
                    Brratu: Unit trains
            Brrc: Car operations (Railroads)
                Brrca: Car utilization (Railroads)
                    Brrcae: Empty cars (Railroads)
                Brrcb: Car supply (Railroads)
                Brrcc: Car shortages (Railroads)
                Brrcd: Car distribution (Railroads)
                Brrce: Car location (Railroads)
                    Brrcet: Car tracing (Railroads)
                Brrci: Car interchange (Railroads)
                Brrcn: Car ownership (Railroads)
                Brrcp: Car pooling (Railroads)
                Brrcq: Car rentals (Railroads)
                Brrcs: Car clearances (Railroads)
            Brrm: Locomotive operations
                Brrma: Locomotive utilization
            Brrq: Operating rules
            Brrr: Car service rules
            Brrs: Interchange rules
        Brs: Vessel operations
            Brsc: Merchant fleet operation
                Brscc: Cargo preference
                Brscd: Cabotage
                Brscr: Registry
                Brscs: Flags of convenience
            Brsd: Ship operations
                Brsdb: Ship's papers
                Brsdc: Ship classification
                Brsde: Ship management
                Brsdj: Ship outfitting
                Brsdk: Seakeeping
                Brsdm: Manning requirements
                Brsdt: Turnaround time
                Brsdu: Bunkering
                Brsdw: Watchkeeping
                Brsdy: Icebreaking
            Brsg: Barge operations
                Brsgt: Barge trains
            Brsn: Towboat operations
            Brsp: Tug ship interaction
            Brsy: Amphibious operations
        Brt: Container utilization
        Bru: Transit vehicle operations
            Brub: Bus transit operations
                Brubc: Run cutting
                Brube: Timed transfer
                Brubf: One man operation
                Brubp: Bus priority
                Brubx: Person capacity
    Bt: Traffic
        Bta: Traffic by mode
            Btaa: Air traffic
                Btaam: Airport traffic
                    Btaamg: Ground traffic
            Btah: Highway traffic
                Btahb: Bus traffic
                Btaht: Truck traffic
            Btar: Railroad traffic
            Btas: Pipeline traffic
            Btaw: Water traffic
                Btawi: Inland waterways traffic
                Btawp: Port traffic
                    Btawpc: Port congestion
            Btax: Transit traffic
        Btb: Types of traffic
            Btbd: Diverging traffic
            Btbm: Merging traffic
            Btbn: Opposing traffic
            Btbp: Peak hour traffic
            Btbr: One way traffic
            Btbs: Single lane traffic
            Btbt: Through traffic
        Bte: Traffic measurement
            Btea: Traffic data
                Bteaf: Floating car data
            Bteb: Vehicle miles of travel
            Btec: Adjustment factors
            Bted: Measures of effectiveness
            Bteh: Person miles of travel
            Btem: Traffic counting
            Btep: Passenger counting
            Btes: Traffic counting stations
            Btet: Traffic counts
                Btetc: Cordon counts
                Btetm: Manual traffic counts
        Btf: Traffic models
            Btfa: Macroscopic traffic flow
            Btfb: Microscopic traffic flow
            Btfc: Mesoscopic traffic flow
            Btfs: Traffic simulation
        Bth: Traffic characteristics
            Btha: Traffic assignment
                Bthad: Dynamic traffic assignment
            Bthb: Traffic incidents
            Bthc: Traffic conflicts
            Bthd: Traffic delay
                Bthds: Stopped time delay
            Bthe: Traffic density
            Bthf: Traffic flow
                Bthfc: Traffic congestion
                    Bthfcd: Nonrecurrent congestion
                Bthfe: Concurrent flow
                Bthfh: Saturation flow
                    Bthfho: Oversaturation (Traffic flow)
                Bthfi: Interrupted flow
                Bthfj: Uninterrupted flow
                Bthfk: Bottlenecks
                Bthfq: Traffic flow rate
                Bthfr: Traffic flow theory
                Bthfu: Traffic equilibrium
            Bthg: Gap acceptance
            Bthh: Traffic diversion
                Bthhd: Detours
            Bthj: Traffic distribution
                Bthjd: Directional distribution
                Bthjk: Lane distribution
                    Bthjkn: Lane occupancy
                    Bthjkp: Lateral placement
            Bthk: Vehicle spacing
                Bthkb: Bunching
                Bthkc: Car following
                Bthkf: Following distance
                Bthkh: Headways
                Bthkp: Traffic platooning
                Bthkt: Tailgating
            Bthm: Vehicle mix
            Bthn: Traffic queuing
            Bthq: Stopping
                Bthqd: Stopping distances
            Bthr: Traffic relationships
                Bthrf: Flow speed relationships
                Bthrs: Speed volume relationships
            Bths: Traffic speed
                Bthsb: Operating speed
                Bthsd: Speed distribution
                Bthse: Speed and delay studies
                Bthsm: Speed measurement
                    Bthsma: Average travel speed
                    Bthsmp: 85th percentile speed
                Bthsq: Free flow speeds
                Bthsr: Running speed
                Bthss: Spot speed
                    Bthssa: Average spot speed
                Bthst: Speed data
                Bthsv: Design speed
            Btht: Sight distance
                Bthtp: Passing sight distance
                Bthts: Stopping sight distance
            Bthu: Turning traffic
                Bthum: Left turns
                    Bthumm: Left turn on red
                Bthur: Right turns
                    Bthurr: Right turn on red
                Bthuu: U turns
            Bthv: Traffic volume
                Bthva: Average daily traffic
                    Bthvaa: Annual average daily traffic
                Bthvd: Design volume
                    Bthvdh: Design hourly volume
                Bthvm: Link volume
                Bthvp: Passenger car equivalence
            Bthw: Weaving traffic
            Bthx: Traffic surveys
    Bu: Offroad traffic
    Bx: Pedestrian movement
        Bxc: Pedestrian counts
        Bxd: Pedestrian density
        Bxf: Pedestrian flow
        Bxj: Pedestrian vehicle interface
        Bxt: Pedestrian traffic
        Bxw: Walking distance
C: Management and organization
    Ca: Management
        Caa: Administration
            Caaa: Public administration
        Cad: Auditing
        Cam: Participatory management
        Cap: Program management
        Car: Project management
            Cark: Construction projects
            Carm: Megaprojects
        Cat: Crisis management
        Caw: Total quality management
    Cb: Operations
        Cbd: Business practices
        Cbp: Procedures
    Cc: Human resources management
        Ccb: Personnel management
            Ccba: Job analysis
                Ccbat: Task analysis
                    Ccbats: Time and motion studies
            Ccbb: Selection and appointment
                Ccbbh: Hiring policies
                Ccbbr: Recruiting
            Ccbk: Working conditions
                Ccbkb: Work rules
                Ccbkc: Crew size
                Ccbkd: Workload
                Ccbke: Work measurement
                Ccbkh: Hours of labor
                    Ccbkhf: Flexible hours
                    Ccbkhh: Staggered work hours
                    Ccbkhm: Four day week
                    Ccbkhr: Rest periods
                    Ccbkhs: Shifts
                        Ccbkhsn: Night shifts
                Ccbkp: Crew accommodation
                Ccbkq: Crew comfort
                Ccbkr: Clothing
                    Ccbkru: Uniforms
                Ccbkx: Leisure time
                    Ccbkxr: Recreation
                        Ccbkxrb: Boating
                        Ccbkxrh: Hiking
                        Ccbkxrj: Skating
                        Ccbkxrp: Outdoor recreation
                        Ccbkxrs: Sports
                            Ccbkxrsn: Racing
                            Ccbkxrss: Soccer
                    Ccbkxv: Vacations
                Ccbky: Work environment
                    Ccbkyg: Work area
                    Ccbkyi: Industrial hygiene
                    Ccbkym: Workplace layout
            Ccbm: Employee compensation
                Ccbmb: Pay
                    Ccbmbs: Salaries
                    Ccbmbw: Wages
                Ccbmg: Employee benefits
                    Ccbmgc: Workers compensation
                    Ccbmgp: Pensions
                    Ccbmgr: Profit sharing
                    Ccbmgs: Employee ownership
                        Ccbmgse: Employee stock ownership plans
            Ccbp: Employee relations
                Ccbpb: Employee assistance programs
                Ccbpc: Employee communications
                Ccbpd: Discrimination
                Ccbpe: Counseling
                Ccbph: Sexual harassment
                Ccbpi: Interviewing
                Ccbpj: Employee participation
                    Ccbpje: Employee empowerment
                    Ccbpjq: Quality circles
                Ccbpk: Personnel development
                Ccbpm: Personnel motivation
                    Ccbpma: Awards
                    Ccbpmj: Job satisfaction
                    Ccbpmm: Morale
                    Ccbpms: Grievances
            Ccbq: Deployment
            Ccbr: Personnel performance
                Ccbra: Absenteeism
                Ccbrd: Discipline
                Ccbrq: Performance evaluations
                    Ccbrqq: Quality of work
                    Ccbrqs: Self evaluation
            Ccbs: Supervision
            Ccbt: Personnel retention
            Ccbu: Terminations
                Ccbud: Dismissal
                Ccbug: Turnover
                Ccbur: Retirement
                    Ccbure: Employee buyouts
                Ccbus: Layoffs
            Ccbw: Ethics
                Ccbwc: Conflict of interest
                Ccbwm: Medical ethics
                Ccbws: Corruption
        Ccm: Leadership
    Ce: Education and training
        Cec: Curricula
        Cee: Examinations
        Cek: Education
            Cekc: Continuing education
            Ceky: Graduate study
        Cet: Training
            Cete: Emergency training
            Cetp: Training programs
            Cetr: Retraining
            Cets: Specialized training
        Ceu: Certification
        Cex: Education and training methods
            Cexc: Computer aided instruction
            Cexf: Distance learning
            Cexp: Programmed instruction
        Cey: Vocational guidance
    Cf: Finance
        Cfa: Revenues
            Cfaa: Operating revenues
            Cfab: Income
            Cfac: Earnings
            Cfad: Yield (Finance)
                Cfady: Yield management
            Cfaf: Financing
                Cfafp: Pooled funds
            Cfau: Appropriations
        Cfb: Expenses
            Cfbu: Expenditures
                Cfbuc: Capital expenditures
        Cfc: Costs
            Cfca: Types of costs
                Cfcab: Operating costs
                Cfcac: Capital costs
                Cfcad: Direct costs
                Cfcaf: Fixed costs
                Cfcaj: Indirect costs
                Cfcak: Labor costs
                Cfcam: Marginal costs
                Cfcap: Overhead costs
                Cfcau: Unit costs
                Cfcav: Variable costs
            Cfcb: Benefit cost analysis
                Cfcbr: Cost effectiveness
            Cfcc: Cost control
                Cfccp: Cost overruns
            Cfcd: Cost allocation
            Cfce: Cost estimating
            Cfcf: Cost sharing
            Cfcj: Cost indexes
            Cfck: Least overall cost
            Cfcr: Cost recovery
            Cfcw: Cost finding
            Cfcx: Estimates
        Cfd: Taxes
            Cfda: Types of taxes
                Cfdac: Carbon taxes
                Cfdaf: Fuel taxes
                Cfdas: Sales tax
                Cfdat: Property taxes
            Cfdr: Taxation
                Cfdra: Highway user taxation
                Cfdrn: Apportionment
                Cfdrs: State taxation
            Cfdt: Tax receipts
        Cfe: Assets
            Cfec: Capital
            Cfeh: Hedging (Finance)
            Cfei: Investments
                Cfeic: Capital investments
            Cfem: Asset management
            Cfes: Securities
                Cfesb: Bonds
                    Cfesbs: Surety bonds
                Cfess: Stocks
        Cff: Liabilities
            Cffd: Debt
            Cffw: Deficits
        Cfg: Equity (Finance)
        Cfh: Government funding
            Cfhg: Grant aid
                Cfhgf: Federal aid
                    Cfhgff: Federal assistance programs
                        Cfhgffr: Relocation assistance
                Cfhgs: State aid
            Cfhs: Subsidies
                Cfhsb: Operating subsidies
                Cfhsd: User side subsidies
                Cfhsf: Cross subsidization
        Cfi: Loans
            Cfig: Government guaranty
            Cfii: Interest rates
        Cfj: Credit
            Cfjc: Credit cards
        Cfk: Fees
            Cfka: Impact fees
            Cfkj: Landing fees
            Cfkr: Registration fees
        Cfm: User charges
        Cfp: Appraisals
        Cfs: Sales
            Cfsd: Discount
            Cfsm: Market value
            Cfsp: Pricing
                Cfspc: Cost of service pricing
                Cfspd: Value of service pricing
                Cfspr: Road pricing
                    Cfsprc: Congestion pricing
            Cfsq: Profits
                Cfsqb: Profitability
            Cfsu: Prices
        Cfu: Assessments
        Cfv: Valuation
            Cfvv: Present value
        Cfy: Bankruptcy
    Cg: Accounting
        Cga: Financial analysis
            Cgac: Cash flow
            Cgaf: Financial ratios
                Cgafm: Operating ratios
                Cgafr: Rate of return
                Cgaft: Return on investment
        Cgb: Budgeting
            Cgbt: Travel budgets
        Cgc: Cost accounting
        Cgk: Depreciation
        Cgm: Amortization
        Cgr: Records management
            Cgrk: Recordkeeping
        Cgu: Billing
        Cgv: Payment
    Ch: Marketing
        Cha: Market assessment
        Chd: Market development
        Chm: Customer service
        Chq: Advertising
            Chqa: Attention value
            Chqm: Mass media
            Chqp: Campaigns
            Chqq: Advertising campaigns
            Chqr: Roadside advertising
            Chqt: Frequent flyer programs
        Chr: Market research
        Chs: Market surveys
        Chv: Shopping
            Chvh: Home shopping
            Chvt: Teleshopping
    Cj: Public relations
        Cjj: Publicity
            Cjjp: Printed publicity
        Cjp: Promotion
        Cjx: Public information programs
    Cm: Logistics
        Cmb: Purchasing
            Cmbg: Procurement
        Cmh: Warehousing
        Cmk: Inventory
            Cmka: Inventory control
            Cmkm: Materials management
            Cmks: Stockpiling
        Cmm: Packaging
        Cmo: Supply chain management
        Cmp: Physical distribution
        Cmr: Inbound transportation
    Cn: Insurance
        Cnb: Risk management
            Cnba: Risk analysis
        Cng: Insurance rates
        Cnj: Insurance claims
        Cnr: Liability
            Cnrf: Financial responsibility
            Cnrg: Government liability
            Cnrp: Products liability
            Cnrs: Tort liability
        Cnv: Liability insurance
            Cnvc: Cargo insurance
            Cnvh: Automobile insurance
                Cnvhk: No fault insurance
            Cnvs: Marine insurance
                Cnvsh: Hull insurance
        Cnw: Self insurance
        Cny: Indemnity
    Cp: Production
        Cpc: Product development
        Cpg: Production methods
            Cpgj: Just in time production
            Cpgs: Series production
        Cpk: Production control
            Cpkp: Productivity
                Cpkpc: Capital productivity
                Cpkpm: Labor productivity
                    Cpkpmd: Downtime
                    Cpkpmi: Idle time
                    Cpkpms: Time sharing
                    Cpkpmw: Waiting time
            Cpks: Sequencing
        Cpm: Manufacturing
            Cpma: Assembly lines
            Cpmb: Flexible manufacturing systems
            Cpmc: Quality control
                Cpmcs: Statistical quality control
            Cpmd: Manufacturing standards
            Cpmq: Quality assurance
            Cpmt: Remanufacturing
            Cpmw: Warranty
        Cpo: Mechanization
        Cpp: Output
            Cppp: Products
                Cpppn: New products
        Cpx: Fault tree analysis
    Cq: Property management
        Cqa: Property acquisition
        Cqc: Property condemnation
            Cqcb: Abandonment
            Cqcd: Eminent domain
            Cqcp: Taking (Property)
        Cqd: Property values
            Cqda: Unearned increment
            Cqdr: Rent
        Cqe: Right of way (Land)
            Cqea: Access control (Transportation)
            Cqeg: Easements
                Cqegs: Scenic easements
        Cqf: Development rights transfer
        Cqg: Airspace utilization
        Cqi: Industrial location
            Cqip: Plant location
        Cqm: Residential location
        Cqp: Ownership, leasing and rental
            Cqpd: Ownership
                Cqpdb: Build operate transfer
            Cqpm: Leasing
                Cqpme: Equipment leasing
                Cqpmg: Cross border leasing
        Cqs: Real estate development
            Cqsd: Land subdivision
    Cr: Policy, legislation and regulation
        Cra: Policy
            Craa: Policy analysis
            Cram: Policy making
            Crap: Public policy
            Crat: Transportation policy
                Crata: Air transportation policy
                    Cratam: Open skies
                Cratu: Urban transportation policy
                    Cratut: Travel demand management
                        Cratutc: Traffic calming
                        Cratutm: Traffic mitigation
                        Cratutt: Traffic restraint
                            Cratutts: Street closure
        Crd: Branches of law
            Crda: Air law
            Crdc: Constitutional law
                Crdcf: Federal conflict preemption (Law)
            Crdi: International law
                Crdit: Treaties
            Crdk: Labor law
            Crdm: Maritime law
            Crdr: Railroad law
            Crdt: Highway law
                Crdtp: Per se laws
        Cre: Laws and legislation
            Crea: Laws
                Creaa: Antitrust laws
                Creaf: Federal laws
                Creaj: Implied consent laws
                Creas: State laws
                Creau: Law uniformity
            Creb: Legislation
                Creba: Public hearings
                Crebd: Amendments
                Crebe: Earmarks
                Crebr: Repeal
            Cred: Ordinances
            Creg: Building codes
        Crf: Regulation
            Crfd: Deregulation
            Crfe: Exemption
                Crfea: Agricultural exemption
            Crfm: Consumer protection
            Crfr: Reregulation
            Crft: Regulations
                Crftc: Curfew
                Crftp: Size and weight regulations
                Crftr: Traffic regulations
                    Crftrk: No passing zones
                    Crftrl: Passing zones
                    Crftrp: Parking regulations
                    Crftrr: Right of way (Traffic)
                    Crftrs: Speed limits
                        Crftrsa: 55 mph speed limit
                        Crftrsb: 65 mph speed limit
                    Crftrt: Speed zones
            Crfw: Regulatory reform
            Crfx: Regulatory constraints
        Crg: Registration
            Crgr: Registrations
        Crh: Licensing
            Crhd: Driver licensing
                Crhdd: Driving tests
                Crhdg: Graduated licensing
            Crhm: Motor vehicle licensing
            Crhy: Licenses
                Crhym: Driver licenses
                    Crhymc: Confiscation
                    Crhymr: Revocation
                    Crhyms: Suspensions
        Cri: Permits
        Crk: Compliance
        Crl: Conformity
        Crm: Administrative procedures
        Crn: Oversight
        Crp: Politics
            Crpf: Political factors
            Crpl: Lobbying
        Cru: Conflict management
            Crud: Disputes
    Cs: Jurisprudence and judicial processes
        Csa: Judicial processes
            Csai: Immunity (Law)
                Csais: Sovereign immunity
        Csb: Litigation
        Csc: Courts
            Csca: Court operations
            Cscb: Court decisions
            Csct: Traffic courts
        Csd: Trials
        Cse: Evidence
            Csee: Expert evidence
        Csf: Penalties
            Csff: Fines (Penalties)
        Csg: Prosecution
        Csh: Appeals
        Csi: Adjudication
            Csij: Justice
                Csijb: Criminal justice
                Csijc: Environmental justice
                Csije: Equity (Justice)
        Csj: Sanctions
        Csk: Probation
        Csm: Legal factors
            Csma: Legal action
            Csmc: Legal constraints
            Csmp: Legal responsibility
            Csmr: Legal rights
                Csmrc: Civil rights
                    Csmrcp: Privacy
                Csmrw: Water rights
    Ct: Trade
        Cta: Retail trade
            Ctaf: Franchises
        Ctb: Wholesale trade
        Ctc: Interstate commerce
        Ctf: International trade
            Ctfe: Exports
            Ctfi: Imports
            Ctfr: Currency adjustment factor
            Ctfu: Ports of entry
                Ctfuc: Customs administration
        Ctm: Electronic commerce
        Ctr: Trade restrictions
    Cu: Contract administration
        Cua: Contracting
            Cuac: Contracting out
            Cuas: Solicitations
        Cub: Bids
            Cubc: Competitive bidding
            Cubj: Incentives
            Cubk: Disincentives
            Cubr: Bid rigging
        Cue: Brokerage
        Cut: Contracts
    Cw: Research management
        Cwa: Prequalifications
        Cwd: Qualifications
        Cwe: Proposals
        Cwf: Applications
        Cwg: Technical writing
        Cwi: Implementation
        Cwt: Recommendations
        Cwu: Utilization
    Cx: Interorganizational relations
        Cxc: Competition
            Cxcb: Market share
            Cxcd: Market dominance
            Cxcn: Barriers to entry (Competition)
        Cxe: Consensus
        Cxf: Cooperation
            Cxfj: Joint use
            Cxfk: Multiple use
        Cxh: Coordination
    Cy: Industry structure
        Cya: Market structure
        Cyb: Vertical integration
        Cyc: Horizontal integration
        Cyd: Decentralization
        Cye: Diversification
        Cyf: Restructuring
            Cyfd: Downsizing
        Cyg: Organization
            Cygb: Organizational effectiveness
            Cygd: Reorganization
        Cyj: Joint ventures
            Cyjc: Consortia
        Cym: Mergers and acquisitions
            Cyma: Consolidations
            Cyme: Mergers
            Cymn: Leveraged buyouts
        Cyp: Privatization
        Cyq: Nationalization
D: Communication and control
    Dc: Control
        Dcb: Automation
        Dcg: Control systems
            Dcga: Actuating systems
            Dcgb: Adaptive control
                Dcgbs: Self organizing systems
            Dcgc: Automatic control
            Dcgd: Command and control systems
            Dcge: Electronic control
            Dcgf: Feedback control
            Dcgh: Fluidics
            Dcgi: Integrated systems
            Dcgj: Intelligent control systems
            Dcgk: Kalman filtering
            Dcgl: Linear systems
                Dcglm: Linear control systems
            Dcgm: Manual control
            Dcgn: Nonlinear systems
            Dcgp: Numerical control
            Dcgr: Process control
                Dcgrd: Distributed control
                Dcgrf: Feedforward control
            Dcgt: Real time control
            Dcgu: Remote control
                Dcgur: Radio control
            Dcgw: Sliding mode control
        Dch: Properties of control systems
            Dche: Equilibrium (Systems)
            Dchg: Fault tolerance
            Dchh: Interoperability
            Dchi: Hysteresis
            Dchm: Linearity
            Dchp: Sensitivity
            Dchr: Stability criteria
            Dchs: Systems availability
            Dcht: Transfer functions
        Dcj: Control devices
            Dcja: Actuators
            Dcjb: Automatic controllers
                Dcjbf: Fuzzy controllers
            Dcjd: Control consoles
                Dcjdd: Control panels
            Dcjm: Loops (Control systems)
            Dcjp: Permanent magnets
            Dcjr: Robots
                Dcjrm: Mobile robots
            Dcjs: Servomechanisms
                Dcjss: Servomotors
            Dcjt: Thyristors
            Dcju: Timers
        Dcm: Control system applications
            Dcmc: Electronic funds transfer
                Dcmcb: Automated toll collection
                Dcmcf: Automatic fare collection
                Dcmcp: Electronic payment (Parking)
                Dcmcr: Automated accounting equipment
                    Dcmcrm: Magnetic farecards
                    Dcmcrs: Smart cards
            Dcmg: Command guidance
            Dcmm: Control in manufacturing
                Dcmmb: Automated guided vehicle systems
                Dcmmd: Computer aided manufacturing
                Dcmmr: Industrial robots
            Dcmt: Traffic control
                Dcmtb: Air traffic control
                    Dcmtbc: Advanced automation system (Air traffic control)
                    Dcmtbf: Air traffic control radar beacon system
                        Dcmtbfm: Mode S
                    Dcmtbj: Aircraft separation
                    Dcmtbm: Approach control
                    Dcmtbp: Automated radar terminal system
                    Dcmtbr: Enroute traffic control
                    Dcmtbt: Flight information services
                    Dcmtbu: Flow control (Air traffic control)
                        Dcmtbum: Metering (Air traffic control)
                    Dcmtbv: Free flight (Air traffic control)
                    Dcmtbw: Radar air traffic control
                    Dcmtbx: Terminal air traffic control
                        Dcmtbxc: Airport surface traffic control
                Dcmth: Highway traffic control
                    Dcmthc: Highway traffic control systems
                        Dcmthca: Advanced traffic management systems
                        Dcmthcc: Congestion management systems
                        Dcmthcd: Lane closure
                        Dcmthcf: Freeway management systems
                            Dcmthcfm: Mainline metering
                            Dcmthcfr: Ramp metering
                        Dcmthcg: Grade crossing protection systems
                        Dcmthcj: Incident management
                        Dcmthcp: Positive guidance
                        Dcmthcs: Signalization
                            Dcmthcse: Traffic signal control systems
                                Dcmthcseb: Area traffic signal control
                                Dcmthcsep: Progressive traffic signal control
                            Dcmthcsk: Traffic signal cycle
                                Dcmthcskj: Traffic signal intervals
                                    Dcmthcskjb: Change interval (Traffic signal cycle)
                                    Dcmthcskjc: Clearance interval (Traffic signal cycle)
                                        Dcmthcskjcp: Pedestrian clearance interval (Traffic signals)
                                    Dcmthcskjg: Green interval (Traffic signal cycle)
                                        Dcmthcskjgb: Bandwidth (Traffic signals)
                                    Dcmthcskjr: Red interval (Traffic signal cycle)
                                    Dcmthcskjy: Yellow interval (Traffic signal cycle)
                                Dcmthcskp: Traffic signal phases
                                    Dcmthcskpr: Phasing by right of way
                                        Dcmthcskpre: Exclusive phasing
                                        Dcmthcskprp: Permissive phasing
                                        Dcmthcskprs: Exclusive permissive phasing
                                    Dcmthcskpt: Phases by type of traffic
                                        Dcmthcskptm: Left turn phase
                                        Dcmthcskptp: Pedestrian phase
                                        Dcmthcskptv: Vehicular phase
                            Dcmthcsm: Traffic signal indications
                            Dcmthcsp: Traffic signal preemption
                            Dcmthcsv: Traffic signal timing
                                Dcmthcsvp: Offsets (Traffic signal timing)
                        Dcmthct: Speed control
                        Dcmthcw: Work zone traffic control
                            Dcmthcwt: Tapers (Work zone traffic control)
                    Dcmthr: Traffic control devices
                        Dcmthrb: Warning devices for the handicapped
                            Dcmthrbb: Audible warning devices
                            Dcmthrbd: Detectable warning surfaces
                        Dcmthrc: Guideposts
                            Dcmthrcm: Mileposts
                        Dcmthre: Highway delineators
                        Dcmthrg: Traffic cones
                        Dcmthrk: Traffic signs
                            Dcmthrkb: Traffic signs by purpose
                                Dcmthrkbg: Guide signs
                                    Dcmthrkbgd: Direction signs
                                    Dcmthrkbgr: Route signs
                                Dcmthrkbr: Regulatory signs
                                    Dcmthrkbrq: Speed signs
                                    Dcmthrkbrs: Stop signs
                                        Dcmthrkbrsm: Multiway stop signs
                                    Dcmthrkbry: Yield signs
                                Dcmthrkbw: Warning signs
                            Dcmthrkk: Traffic signs by characteristics
                                Dcmthrkkj: Illuminated traffic signs
                                Dcmthrkkn: Overhead traffic signs
                                Dcmthrkkr: Reflective signs
                                Dcmthrkks: Symbol signs
                                Dcmthrkkv: Variable message signs
                            Dcmthrks: Traffic signs by audience
                                Dcmthrksp: Pedestrian signs
                        Dcmthrr: Traffic signal hardware
                            Dcmthrrc: Traffic signal controllers
                                Dcmthrrcb: Actuated traffic signal controllers
                                    Dcmthrrcbp: Pedestrian actuated controllers
                                    Dcmthrrcbt: Traffic actuated controllers
                                        Dcmthrrcbtf: Full traffic actuated controllers
                                        Dcmthrrcbts: Semi traffic actuated controllers
                                Dcmthrrcp: Pretimed traffic signal controllers
                            Dcmthrrs: Traffic signals
                                Dcmthrrsb: Parts of traffic signals
                                    Dcmthrrsbh: Signal head
                                        Dcmthrrsbhf: Signal face
                                Dcmthrrsk: Types of traffic signals
                                    Dcmthrrskb: Audible pedestrian signals
                                    Dcmthrrskf: Flashing traffic signals
                                    Dcmthrrskm: Lane use control signals
                        Dcmthru: Road markings
                            Dcmthruc: Center lines
                            Dcmthrue: Edge lines
                            Dcmthrum: Lane lines
                            Dcmthrur: Raised road markings
                                Dcmthrurr: Reflectorized road markings
                            Dcmthruu: Rumble strips
                        Dcmthrx: Speed control humps
                    Dcmthw: Warrants (Traffic control devices)
                Dcmtr: Railroad traffic control
                    Dcmtrg: Grade crossing protection systems
                    Dcmtrs: Railroad signaling
                        Dcmtrsb: Block signal systems
                            Dcmtrsbb: Automatic block signal systems
                        Dcmtrsc: Centralized traffic control
                    Dcmtry: Railroad traffic control devices
                        Dcmtrys: Railroad signals
                            Dcmtrysc: Cab signals
                            Dcmtrysw: Wayside signals
                        Dcmtryt: Track circuits
                Dcmtv: Vessel traffic control
                    Dcmtvh: Harbor traffic control
            Dcmv: Automated vehicle control
                Dcmvb: Guidance systems (Aircraft)
                    Dcmvbf: Flight control systems
                    Dcmvbm: Automatic landing systems
                    Dcmvbp: Automatic pilot
                Dcmvg: Automated vehicle control for ground vehicles
                    Dcmvgm: Longitudinal control
                        Dcmvgmb: Automatic braking
                        Dcmvgmh: Automatic headway control
                            Dcmvgmhb: Asynchronous control
                            Dcmvgmhq: Quasi synchronous control
                            Dcmvgmhs: Synchronous control
                        Dcmvgms: Automatic speed control
                            Dcmvgmsi: Intelligent speed adaptation
                    Dcmvgp: Merging control
                    Dcmvgt: Traction control
                        Dcmvgtb: Active suspension systems
                        Dcmvgtf: Antilock brake systems
                    Dcmvgy: Control of specific ground vehicles
                        Dcmvgyc: Advanced vehicle control systems
                            Dcmvgycb: Automated highway systems
                            Dcmvgycd: Driver support systems
                            Dcmvgych: Automatic steering control
                            Dcmvgycj: Autonomous intelligent cruise control
                        Dcmvgyf: Automatic train control
                            Dcmvgyfd: Automatic train operation
                                Dcmvgyfdj: Jerk control
                            Dcmvgyfm: Automatic train protection
                            Dcmvgyfr: Automatic train stop system
                            Dcmvgyfu: Automatic train supervision
                            Dcmvgyfx: Block control systems
                                Dcmvgyfxf: Fixed block control
                                Dcmvgyfxm: Moving block control
                            Dcmvgyfy: Positive train control
                        Dcmvgyg: Automated guideway transit
                            Dcmvgygp: Personal rapid transit
                        Dcmvgyh: Autonomous vehicle guidance
                Dcmvr: Trajectory control
                Dcmvs: Automatic vessel control
                    Dcmvsb: Automatic pilot
                    Dcmvsm: Dynamic positioning
                    Dcmvsv: Voyage management systems
        Dcn: Navigation
            Dcnb: Navigation processes
                Dcnbd: Dead reckoning
                Dcnbk: Homing
                Dcnbp: Position fixing
                Dcnbs: Pilotage and driving
                    Dcnbsc: Pilotage
                        Dcnbscb: Aircraft pilotage
                            Dcnbscbb: Flight training
                            Dcnbscbg: Instrument flying
                            Dcnbscbh: Visual flight
                            Dcnbscbk: Landing
                                Dcnbscbkb: Crash landing
                                Dcnbscbkd: Ditching
                            Dcnbscbt: Takeoff
                            Dcnbscbu: Taxiing
                            Dcnbscbv: Turning (Aircraft pilotage)
                        Dcnbscs: Ship pilotage
                            Dcnbscsd: Docking
                            Dcnbscsj: Ice navigation
                            Dcnbscsn: Maneuvering
                                Dcnbscsnc: Conning
                            Dcnbscss: Mooring
                                Dcnbscssb: Anchoring
                    Dcnbst: Driving
                        Dcnbsta: Backing (Driving)
                        Dcnbstb: Braking
                            Dcnbstbd: Dynamic braking
                        Dcnbstg: Gear shifting
                        Dcnbstm: Lane changing
                        Dcnbstp: Passing
                        Dcnbstr: Starting (Driving)
                            Dcnbstrc: Cold starts (Driving)
                            Dcnbstrh: Hot starts (Driving)
                        Dcnbsts: Steering
                        Dcnbsty: Driving specific motor vehicles
                            Dcnbstyb: Automobile driving
                            Dcnbstyd: Bus driving
                            Dcnbstym: Motorcycle driving
                            Dcnbstyt: Truck driving
                        Dcnbstz: Driving cessation
            Dcns: Navigational aids
                Dcnsb: Navigation systems
                    Dcnsbb: Celestial navigation
                    Dcnsbc: Collision avoidance systems
                    Dcnsbd: Doppler navigation
                    Dcnsbe: Electronic navigation
                    Dcnsbh: Hyperbolic navigation
                    Dcnsbj: Inertial navigation systems
                    Dcnsbq: Radar
                        Dcnsbqb: Continuous wave radar
                        Dcnsbqc: Doppler radar
                        Dcnsbqd: Drone radar
                        Dcnsbqf: Ground penetrating radar
                        Dcnsbqj: Laser radar
                            Dcnsbqjp: Optical radar
                        Dcnsbqm: Search radar
                            Dcnsbqmn: Navigation radar
                        Dcnsbqp: Side looking radar
                        Dcnsbqs: Terrain avoidance radar
                        Dcnsbqv: Weather radar
                    Dcnsbs: Radio navigation
                        Dcnsbsm: Loran
                            Dcnsbsmc: Loran C
                        Dcnsbsp: Omega navigation system
                        Dcnsbsv: Very high frequency omnidirectional radio range
                    Dcnsbt: Satellite navigation systems
                        Dcnsbtg: Global Positioning System
                        Dcnsbtm: Maritime mobile satellite system
                        Dcnsbtn: NAVSTAR
                    Dcnsbu: Sonic navigation
                    Dcnsby: Tracking systems
                        Dcnsbyb: Automatic tracking
                        Dcnsbyr: Radar tracking
                Dcnsj: Navigation charts
                    Dcnsjb: Aeronautical charts
                    Dcnsjn: Nautical charts
                Dcnsp: Navigation devices
                    Dcnspb: Beacons
                        Dcnspbg: Highway beacons
                        Dcnspbj: Obstruction beacons
                        Dcnspbp: Radar beacons
                        Dcnspbs: Radio beacons
                            Dcnspbsw: Warning radio beacons
                    Dcnspc: Compasses
                        Dcnspcg: Gyrocompasses
                    Dcnspd: Gyroscopes
                    Dcnspe: Instrument displays
                        Dcnspeh: Head up displays
                        Dcnspet: Three dimensional displays
                    Dcnspf: Flight recorders
                    Dcnspg: Navigation computers
                        Dcnspgp: Position indicators
                    Dcnspj: Navigation lights
                        Dcnspjp: Pyrotechnics
                    Dcnspm: Navigational satellites
                    Dcnspq: Obstruction markers
                        Dcnspqb: Obstruction buoys
                        Dcnspqm: Obstruction lights
                    Dcnsps: Radar devices
                        Dcnspsb: Radar beacons
                        Dcnspsd: Radar displays
                            Dcnspsdj: Radar images
                                Dcnspsdjc: Radar clutter
                                Dcnspsdjm: Plan position indicators
                                Dcnspsdjt: Radar targets
                            Dcnspsdm: Radar maps
                        Dcnspsm: Moving target indicators
                        Dcnspsr: Radar receivers
                    Dcnspt: Radio navigation devices
                        Dcnsptb: Radio beacons
                            Dcnsptbw: Warning radio beacons
                        Dcnsptd: Radio direction finders
                        Dcnsptf: Emergency locator transmitters
                        Dcnsptt: Transponders
                Dcnsx: Navigational aids by reference to craft
                    Dcnsxb: Aids to navigation
                        Dcnsxbb: Aids to air navigation
                            Dcnsxbbt: Terminal navigation aids
                    Dcnsxp: Onboard navigational aids
                        Dcnsxpb: Airborne navigational aids
                Dcnsy: Navigational aids specific to a craft or vehicle
                    Dcnsyb: Aircraft navigational aids
                        Dcnsybd: Distance measuring equipment
                        Dcnsybm: Landing aids
                            Dcnsybmc: All weather landing systems
                            Dcnsybmg: Glide path systems
                            Dcnsybmj: Instrument landing systems
                            Dcnsybmm: Microwave landing systems
                        Dcnsybp: Stabilized platforms
                        Dcnsybq: Tactical air navigation system
                        Dcnsybt: Traffic alert and collision avoidance system
                    Dcnsyh: Motor vehicle navigational aids
                        Dcnsyhb: Automobile navigation systems
                        Dcnsyhh: Highway beacons
                        Dcnsyhp: Passing aid systems
                        Dcnsyhr: Roadway guidance markers
                    Dcnsys: Ship navigational aids
                        Dcnsysd: Buoys
                            Dcnsysdp: Obstruction buoys
                        Dcnsysm: Lightships
                        Dcnsyss: Sonar
                            Dcnsyssd: Doppler sonar
                            Dcnsysst: Sonar domes
                            Dcnsyssv: Sonar transducers
                        Dcnsysv: Voyage data recorders
                Dcnsz: Distress alerting systems
            Dcnu: Obstructions (Navigation)
                Dcnuc: Clearances (Navigation)
        Dct: Train operation
            Dctm: Locomotive operation
            Dctr: Retarder control
    Dm: Detection and identification
        Dmb: Detection and identification systems
            Dmbj: Identification systems
                Dmbjc: Character recognition
                    Dmbjcp: Optical character recognition
                Dmbjj: Machine vision
                    Dmbjjc: Computer vision
                        Dmbjjcr: Robot vision
                    Dmbjjh: Image analysis
                    Dmbjjk: Image processing
                    Dmbjjp: Pattern recognition systems
                        Dmbjjpe: Edge detection
                    Dmbjjt: Visual texture recognition
                Dmbjs: Radio frequency identification
            Dmbm: Monitoring
            Dmbr: Remote sensing
            Dmbt: Surveillance
            Dmby: Detection and identification system applications
                Dmbyb: Automatic car identification
                Dmbyc: Automatic train location
                Dmbye: Automatic equipment identification
                Dmbyp: Driver monitoring
                Dmbyr: Fault monitoring
                Dmbyt: Traffic surveillance
                    Dmbytj: Incident detection
                        Dmbytjb: Automatic incident detection
                Dmbyv: Automatic vehicle detection and identification systems
                    Dmbyvc: Automatic vehicle classification
                    Dmbyvj: Automatic vehicle identification
                    Dmbyvm: Automatic vehicle location
                    Dmbyvp: Automatic vehicle monitoring
                    Dmbyvw: Weigh in motion
                    Dmbyvy: Automated clearance
        Dmg: Detection and identification devices
            Dmgd: Detectors
                Dmgde: Types of detectors
                    Dmgdeb: Acoustic detectors
                        Dmgdebg: Geophones
                        Dmgdebh: Hydrophones
                        Dmgdebu: Ultrasonic detectors
                    Dmgdee: Infrared detectors
                    Dmgdeh: Loop detectors
                    Dmgdek: Magnetic detectors
                    Dmgdem: Magnetometer detectors
                    Dmgdeq: Microwave detectors
                    Dmgdet: Optical detectors
                    Dmgdeu: Photodetectors
                    Dmgdew: Proximity detectors
                    Dmgdex: Scintillation counters
                    Dmgdey: Video imaging detectors
                        Dmgdeyb: Automatic license plate readers
                Dmgdr: Detectors by object of detection
                    Dmgdre: Explosives detectors
                    Dmgdrg: Gas detectors
                    Dmgdri: Hot box detectors
                    Dmgdrp: Pedestrian detectors
                    Dmgdrr: Radar detectors
                    Dmgdrt: Speed detectors
                    Dmgdrv: Vehicle detectors
                        Dmgdrvr: Radar vehicle detectors
            Dmgm: Landsat satellites
            Dmgr: Rangefinders
                Dmgrp: Optical rangefinders
            Dmgs: Scanners
                Dmgsp: Optical scanners
                    Dmgspb: Bar code scanners
                    Dmgspy: Image fields in optical scanning
                        Dmgspyb: Bar codes
                            Dmgspybt: Universal product codes
                        Dmgspye: Electronic license plates
            Dmgu: Sensors
                Dmgum: In vehicle sensors
                    Dmgume: Crash sensors
                    Dmgumt: Tire pressure monitoring systems
                Dmgut: Temperature sensors
    Ds: Communication
        Dsb: Communication systems
            Dsbb: Data communications
                Dsbbe: Electronic data interchange
                Dsbbm: Electronic mail
                Dsbbp: Image transmission
                Dsbbs: Self describing data
                Dsbbt: Transborder data flow
            Dsbd: Digital communication systems
                Dsbdd: Digital subscriber lines
                Dsbdm: Multi access systems
                    Dsbdmc: Access control (Communications)
                        Dsbdmcc: Carrier sense multiple access
                        Dsbdmcg: Code division multiple access
                        Dsbdmcn: Demand assigned multiple access
                        Dsbdmcr: Frequency division multiple access
                        Dsbdmcu: Time division multiple access
            Dsbe: Facsimile
            Dsbg: Information display systems
                Dsbgd: Data displays
                Dsbgg: Digital displays
                    Dsbgge: Digital video
                    Dsbggm: Liquid crystal displays
            Dsbk: Meteor burst communications
            Dsbm: Microwave communication systems
                Dsbmm: Millimeter wave communication systems
            Dsbn: Mobile communication systems
                Dsbnb: Dedicated short range communications
                Dsbnm: Mobile radio
                    Dsbnmb: Mobile telephones
                    Dsbnmc: Cellular radio
                        Dsbnmcb: Cellular telephones
                Dsbnu: Vehicle to roadside communications
                Dsbnw: Vehicle to vehicle communications
            Dsbp: Radio and television
                Dsbpp: Radio
                    Dsbppd: Citizen band radio
                    Dsbppm: Mobile radio
                        Dsbppmc: Cellular radio
                    Dsbppr: Radio links
                    Dsbpps: Radio relay systems
                    Dsbppt: Radio telephone
                    Dsbppv: Selective calling systems
                    Dsbppx: Time signals
                Dsbpv: Television
                    Dsbpvc: Closed circuit television
                    Dsbpvv: Teletext systems
            Dsbq: Satellite communication
            Dsbr: Signaling
                Dsbrh: Hand signaling
            Dsbs: Telecommunications
                Dsbsc: Teleconferencing
                Dsbss: SONET
                Dsbsv: Voice communication
            Dsbt: Telephone
                Dsbtb: Audiotex
            Dsbu: Telex
            Dsbv: Videotext
            Dsbw: Wireless communication systems
                Dsbwb: Bluetooth technology
                Dsbwp: Personal communication networks
            Dsbx: Wideband communication systems
                Dsbxs: Spread spectrum communications
        Dsf: Communication systems by recipient
            Dsfm: Mass communication
            Dsfp: Traveler information and communication systems
                Dsfpb: Advanced traveler information systems
                Dsfpc: Motorist aid systems
                    Dsfpcb: Automatic crash notification
                    Dsfpce: Emergency road service
                    Dsfpcg: Freeway service patrols
                Dsfpd: Driver information systems
                    Dsfpdb: Advanced driver information systems
                    Dsfpdf: Automatic radio information
                    Dsfpdh: Highway advisory radio
                    Dsfpdp: Road weather information systems
                    Dsfpdr: Route guidance
                        Dsfpdrp: Parking guidance systems
                Dsfpp: Passenger information systems
        Dsg: Communication devices
            Dsgc: Communications satellites
            Dsgk: Optical waveguides
            Dsgl: Personal communication devices
            Dsgm: Radio equipment
                Dsgmb: Antennas
                    Dsgmbd: Dipole antennas
                    Dsgmbg: Directional antennas
                    Dsgmbn: Omnidirectional antennas
                    Dsgmbs: Radar antennas
                        Dsgmbsp: Phased arrays
                Dsgmc: Antenna accessories
                    Dsgmcr: Radomes
                Dsgme: Emergency radio equipment
                    Dsgmec: Call boxes (Driver aid devices)
                Dsgmm: Multiplexers
                Dsgmr: Radio receivers
                Dsgmt: Radio transmitters
                Dsgmv: Terminal equipment (Radio)
                Dsgmw: Transceivers
                Dsgmx: Transponders
            Dsgp: Signal devices
                Dsgpk: Signal lights
            Dsgr: Signs
                Dsgrm: Lettering
                Dsgrp: Sign sheeting
                Dsgrs: Symbols
            Dsgs: Suppressors
            Dsgv: Telephone equipment
                Dsgvm: Modems
            Dsgw: Terminals (Communications)
            Dsgx: Transducers
                Dsgxe: Electroacoustic transducers
                Dsgxp: Piezoelectric transducers
                Dsgxz: Vibrating wire transducers
        Dsm: Transmission
            Dsmb: Messages (Communications)
                Dsmbc: Communications traffic
                Dsmbe: Entropy (Communications)
                Dsmbr: Recording
                Dsmbs: Signals
                    Dsmbsb: Arrows (Signals)
                    Dsmbsd: Distress signals
                    Dsmbsr: Radio signals
                    Dsmbst: Strobes
                    Dsmbsw: Warning signals
                Dsmbt: Text messaging
            Dsmm: Transmission techniques
                Dsmmb: Broadcasting
                    Dsmmbb: Digital audio
                    Dsmmbt: Digital television
                Dsmmd: Fiber optics
                Dsmmf: Frequency allocation
                Dsmmh: Line of sight
                Dsmmj: Modulation (Communications)
                    Dsmmjb: Amplitude modulation
                    Dsmmjf: Frequency modulation
                    Dsmmjp: Pulse modulation
                        Dsmmjpc: Pulse code modulation
                        Dsmmjpd: Pulse duration modulation
                Dsmmm: Multiplexing
                    Dsmmmt: Time division multiplexing
                        Dsmmmtp: Packet switching
                Dsmmp: Segmentation (Communications)
                Dsmmr: Signal processing
                    Dsmmrb: Acoustic signal processing
                Dsmmt: Speech recognition
                    Dsmmts: Speech synthesis
                Dsmmv: Telemetry
            Dsmr: Transmission errors and interference
                Dsmrc: Crosstalk
                Dsmrj: Interference
                    Dsmrjc: Atmospheric interference
                    Dsmrje: Electromagnetic interference
                    Dsmrjj: Inductive interference
                    Dsmrjr: Radio frequency interference
                    Dsmrjt: Telephone influence factors
                Dsmrk: Multipath transmission
                Dsmrn: Noise (Communications)
                    Dsmrns: Signal to noise ratio
                Dsmrs: Splitting (Communications)
                Dsmrt: Transmission loss
    Dt: Telematics
        Dtv: Intelligent transportation systems
            Dtvb: ITS program applications
                Dtvbc: Advanced public transportation systems
                Dtvbf: Advanced rural transportation systems
                Dtvbu: Commercial vehicle operations
            Dtvm: ITS program technologies
                Dtvmj: Advanced traffic management systems
                Dtvmn: Advanced traveler information systems
                    Dtvmnd: Advanced driver information systems
                Dtvmr: Advanced vehicle control systems
            Dtvx: Intelligent transportation systems programs
E: Planning and design
    Ep: Planning
        Epd: Planning stages
            Epdb: Evaluation and assessment
                Epdbb: Analysis
                    Epdbbb: Alternatives analysis
                Epdbc: Ratings
                Epdbd: Evaluation
                Epdbe: Technology assessment
                Epdbf: Feasibility analysis
                Epdbn: Needs assessment
                Epdbp: Deficiencies
                Epdbr: Performance measurement
            Epdm: Planning methods
                Epdmc: Contingency planning
                Epdmd: Decision making
                    Epdmdm: Multiple criteria decision making
                Epdmf: Forecasting
                    Epdmfb: Box Jenkins forecasting
                    Epdmfd: Delphi method
                    Epdmft: Technological forecasting
                Epdmk: Long range planning
                Epdmm: Multiple use planning
                Epdmp: Short range planning
                Epdmq: Sketch planning
                Epdms: Strategic planning
                Epdmy: Systems analysis
                    Epdmyn: Network analysis (Planning)
            Epdr: Plan implementation
                Epdrb: Beautification
                Epdrd: Development
                    Epdrdj: Joint development
                    Epdrdm: Mixed use development
                    Epdrdr: Redevelopment
                        Epdrdru: Urban renewal
                    Epdrds: Sustainable development
                    Epdrdt: Transit oriented development
                Epdrh: Historic preservation
                    Epdrhs: Historic sites
                Epdrk: Improvements
                Epdrm: Modernization
                Epdrn: No build
                Epdrp: Programming (Planning)
                Epdrq: Resource allocation
                Epdrs: Scheduling
            Epdu: Planning by facility or land use
                Epdum: Land use planning
                    Epdumb: Master plans
                    Epdumc: City planning
                        Epdumcs: Smart growth
                    Epdumr: Regional planning
                Epdut: Transportation planning
                    Epdutb: Airport planning
                    Epduth: Highway planning
                    Epduts: Sustainable transportation
                    Epdutt: Transportation system management
    Es: Design
        Esd: Design methods
            Esdb: Computer aided design
            Esdc: Earthquake resistant design
                Esdcb: Base isolation
            Esdf: Estimating
            Esdg: Geometric design
            Esdh: Human factors engineering
                Esdhm: Human machine systems
                    Esdhmd: Driver vehicle interfaces
                    Esdhmg: User interfaces (Computer science)
                        Esdhmgg: Graphical user interfaces
            Esdm: Life cycle analysis
                Esdmc: Life cycle costing
            Esdr: Redundancy
            Esds: Systems engineering
                Esdsc: Critical path method
                Esdsp: PERT
                Esdss: System design
            Esdu: Ultimate load design
            Esdw: Wind resistant design
        Esm: Design practices
            Esmd: Design standards
            Esmg: Graphics
                Esmgd: Drafting
                    Esmgdd: Drawdown (Graphics)
                    Esmgdm: Layout
                Esmgh: Imagery
                    Esmghf: Holography
                    Esmghj: Infrared imagery
                    Esmghr: Radiography
                        Esmghrt: Tomography
                    Esmght: Thermal imagery
                Esmgm: Mapping
                    Esmgmd: Digital mapping
                    Esmgmp: Projection (Cartography)
                        Esmgmpb: Azimuthal map projection
                        Esmgmpg: Grids (Coordinates)
                        Esmgmps: Stereographic projection
                Esmgp: Photography
                    Esmgpb: Aerial photography
                    Esmgpe: Color photography
                    Esmgpg: Digitized photography
                    Esmgpk: High speed photography
                    Esmgpp: Infrared photography
                    Esmgpt: Time lapse photography
                    Esmgpx: Underwater photography
            Esmk: Location
                Esmkr: Relocation (Facilities)
                Esmks: Spacing
            Esmm: Materials selection
                Esmmm: Mix design
                Esmmp: Proportioning
                    Esmmpw: Water cement ratio
            Esms: Surveying
                Esmsf: Surveying methods and processes
                    Esmsfb: Aerial surveying
                    Esmsfd: Alignment
                    Esmsff: Geodetic surveying
                    Esmsfj: Photogrammetry
                        Esmsfjb: Aerial photogrammetry
                    Esmsfm: Photointerpretation
                    Esmsfp: Photologging
                    Esmsfq: Referencing
                    Esmsfs: Setting out (Surveying)
                    Esmsft: Triangulation
                Esmsr: Surveying by feature
                    Esmsrb: Archaeological surveying
                    Esmsrg: Geological surveying
                        Esmsrgs: Soil mapping
                        Esmsrgt: Terrain evaluation
                    Esmsrh: Hydrographic surveying
                        Esmsrhh: Hydrographs
                            Esmsrhhf: Flood hydrographs
                            Esmsrhhu: Unit hydrographs
                    Esmsrr: Route surveying
        Ess: Service life
        Est: Serviceability
            Esty: Serviceability of specific facilities or equipment
                Estyd: Pavement distress
                Estyp: Pavement performance
        Esu: Design of specific facilities
            Esuh: Barrier free design
            Esum: Landscape design
                Esumr: Roadside improvement
            Esus: Structural design
                Esusb: Bridge design
                Esush: Highway design
                    Esushb: Context sensitive design
                    Esushc: Traffic channelization
                    Esushp: Pavement design
                        Esushpm: Mechanistic design
                    Esushs: Superelevation
                Esusk: Interior design
            Esuu: Urban design
                Esuus: Streetscape
        Esv: Vehicle design
            Esvs: Streamlining
        Esx: Equipment design
            Esxj: Instrumentation
    Ew: State of the art
        Ewb: Best practices
        Ewc: State of the practice
    Ex: Standardization
    Ey: Innovation
        Eyi: Inventions
        Eyt: Technological innovations
F: Construction and maintenance
    Fc: Construction
        Fca: Building
            Fcac: Bonding and joining
                Fcacb: Bonding
                    Fcacbc: Cladding
                    Fcacbg: Gluing
                Fcacj: Joining
                    Fcacjb: Bolting
                        Fcacjbr: Rock bolting
                    Fcacjs: Splicing
                    Fcacjv: Structural connection
            Fcae: Erection (Building)
            Fcaj: Demolition
            Fcam: Drilling
                Fcamb: Boring
                Fcamr: Rotary drilling
            Fcap: Electrical installation
                Fcapg: Electrical grounding
                Fcaps: Splicing
                Fcapu: Wiring
            Fcat: Pile driving
            Fcau: Positioning
                Fcauk: Leveling
                    Fcaukc: Cross leveling
                Fcaun: Lowering
            Fcaw: Prestressing
            Fcax: Supporting
                Fcaxb: Bracing
                Fcaxe: Embedment (Building)
                Fcaxs: Shoring
            Fcay: Tensioning
                Fcayn: Posttensioning
                Fcays: Pretensioning
        Fcb: Materials adaptation and use
            Fcba: Aeration
            Fcbb: Comminution
                Fcbbc: Crushing
                Fcbbg: Grinding
                Fcbbs: Shredding
            Fcbc: Compaction
                Fcbct: Tamping
                Fcbcv: Vibratory compaction
            Fcbd: Cutting
                Fcbdg: Glazing
                Fcbdm: Sawing
                Fcbdt: Scarifying
                Fcbdw: Sectioning
            Fcbe: Densification
            Fcbg: Drying
                Fcbgp: Oven drying
            Fcbj: Forming
                Fcbjb: Attenuation (Engineering)
                Fcbjc: Casting
                Fcbjd: Curling
                Fcbje: Extrusion
                Fcbjj: Injection molding
                Fcbjr: Reaction injection molding
                Fcbjs: Straightening
            Fcbk: Impregnation (Engineering)
            Fcbl: Machining
            Fcbm: Mechanical analysis
                Fcbme: Filtration
                Fcbmh: Flotation
            Fcbn: Milling
            Fcbp: Mixing
                Fcbpb: Blending
                Fcbpp: Premixing
            Fcbq: Pouring
            Fcbr: Processing (Materials)
            Fcbu: Refining
            Fcbv: Spreading
            Fcbw: Surface preparation
                Fcbwp: Planing
                Fcbws: Sanding
            Fcbx: Wetting
            Fcby: Adaptation and use of specific materials
                Fcbyd: Adaptation and use of bituminous materials
                    Fcbydb: Bituminous construction
                    Fcbydd: Dryer drum process
                Fcbye: Masonry construction
                    Fcbyeb: Brick construction
                    Fcbyeg: Grouting
                    Fcbyep: Plugging
                Fcbyf: Composite construction
                    Fcbyfs: Sandwich construction
                Fcbyg: Concrete construction
                    Fcbygf: Concrete curing
                        Fcbygfb: Autoclave curing
                        Fcbygfm: Membrane curing
                        Fcbygfs: Steam curing
                    Fcbygj: Concrete finishing
                        Fcbygjb: Brooming
                    Fcbygm: Formwork
                    Fcbygo: Joint construction
                    Fcbygp: Joint sealing
                    Fcbygr: Concrete mixing
                    Fcbygt: Concrete placing
                    Fcbygu: Segmental construction
                    Fcbygv: Scoring (Concrete)
                    Fcbygx: Reinforcement (Engineering)
                        Fcbygxm: Longitudinal reinforcement
                        Fcbygxs: Shear reinforcement
                        Fcbygxt: Transverse reinforcement
                Fcbyj: Metal working
                    Fcbyja: Cold working
                    Fcbyjb: Corrugating
                    Fcbyjc: Forging
                        Fcbyjcc: Cold forming
                        Fcbyjch: Hot rolling
                    Fcbyjg: Metal coating
                        Fcbyjge: Electroplating
                        Fcbyjgg: Galvanizing
                            Fcbyjggh: Hot dipping
                        Fcbyjgs: Surfacing
                    Fcbyjj: Preforming
                    Fcbyjm: Metal cutting
                        Fcbyjmf: Flame cutting
                        Fcbyjmn: Notching (Cutting)
                        Fcbyjmp: Plasma arc cutting
                    Fcbyjq: Metal hardening
                        Fcbyjqb: Age hardening
                        Fcbyjqf: Flame hardening
                        Fcbyjqp: Peening
                        Fcbyjqq: Strain hardening
                        Fcbyjqs: Surface hardening
                    Fcbyjs: Metal heating
                        Fcbyjsb: Annealing
                        Fcbyjsn: Sintering
                        Fcbyjsq: Smelting
                        Fcbyjss: Stress relieving
                        Fcbyjst: Tempering
                    Fcbyjt: Trimming
                    Fcbyju: Powder metallurgy
                    Fcbyjv: Welding
                        Fcbyjvb: Automatic welding
                        Fcbyjvd: Electric arc welding
                            Fcbyjvdg: Gas metal arc welding
                            Fcbyjvdj: Inert gas shielded arc welding
                            Fcbyjvds: Submerged arc welding
                        Fcbyjvf: Electron beam welding
                        Fcbyjvh: Electroslag welding
                        Fcbyjvs: Soldering
                            Fcbyjvsb: Brazing
                        Fcbyjvu: Spot welding
                        Fcbyjvw: Thermit welding
                Fcbys: Soil stabilization
                    Fcbysg: Ground freezing
                    Fcbysm: Liming of soils
                    Fcbyss: Soil compaction
                    Fcbyst: Soil densification
                    Fcbysw: Soil nailing
                Fcbyw: Timber construction
        Fcc: Materials and structures protection
            Fccb: Fumigation
            Fccd: Protective coating
                Fccde: Encapsulation
                Fccdp: Painting
                    Fccdpk: Paint removal
                    Fccdpn: Spray painting
                    Fccdps: Spreading rate (Painting)
                Fccds: Sealing (Technology)
                    Fccdss: Stuffing
                    Fccdsu: Undersealing
            Fccm: Protection against environmental damage
                Fccmc: Corrosion protection
                    Fccmcb: Anodic protection
                    Fccmcc: Cathodic protection
                    Fccmcr: Rust prevention
                Fccmf: Frost protection
                Fccmj: Ice prevention
                Fccmw: Weatherproofing
                    Fccmww: Waterproofing
            Fccs: Preservation
            Fccu: Surface treating
        Fcd: Environmental control
            Fcdd: Damping (Engineering)
            Fcdf: Fog dispersal
            Fcdh: Humidity control
            Fcdm: Lighting
            Fcdt: Temperature control
                Fcdtc: Cooling
                    Fcdtcr: Refrigeration
                Fcdth: Heating
                    Fcdthf: Induction heating
                    Fcdthp: Infrared heating
                    Fcdths: Preheating
                    Fcdthu: Reheating
            Fcdv: Vibration control
                Fcdvj: Vibration isolation
        Fce: Construction by environment
            Fcec: Cold weather construction
            Fceh: Hot weather construction
            Fcep: Offshore construction
            Fces: Underground construction
                Fcest: Trenchless technology
                    Fcestp: Pipe bursting
            Fceu: Underwater construction
        Fcf: Construction of specific facilities
            Fcff: Road construction
                Fcffj: Pavement grooving
                Fcffn: Pavement widening
                Fcffp: Paving
                    Fcffps: Slip form paving
                Fcffr: Seal coating
                Fcffs: Striping
            Fcfh: Water control
                Fcfhb: Bank protection
                    Fcfhbs: Shore protection
                Fcfhd: Channel stabilization
                Fcfhe: Dewatering
                Fcfhf: Drainage practices
                    Fcfhfp: Pipe jacking
                Fcfhh: Flood protection
                    Fcfhhf: Flood routing
                    Fcfhhr: River regulation
                Fcfhs: Seepage control
                Fcfhw: Water storage
            Fcfm: Landscaping
                Fcfmc: Cultivation
                Fcfmm: Mulching
                Fcfmp: Planting
                    Fcfmpt: Transplanting
                Fcfms: Seeding
            Fcfn: Pipe laying
            Fcfp: Railroad construction
                Fcfpe: Railroad electrification
                Fcfpt: Track laying
            Fcfx: Excavation and tunneling
                Fcfxe: Excavation
                    Fcfxee: Earthwork
                        Fcfxeeb: Backfilling
                        Fcfxeec: Cutting (Earthwork)
                        Fcfxeeg: Grading (Earthwork)
                    Fcfxeh: Explosive excavation
                        Fcfxehn: Nuclear excavation
                    Fcfxen: Open cut excavation
                    Fcfxer: Rock excavation
                        Fcfxern: Presplitting (Blasting)
                        Fcfxerr: Rock drilling
                            Fcfxerrd: Diamond drilling
                    Fcfxes: Shaft sinking
                    Fcfxet: Trenching
                    Fcfxeu: Underwater excavation
                        Fcfxeud: Dredging
                Fcfxt: Tunneling
                    Fcfxtc: Cut and cover tunneling
                    Fcfxtf: Full face tunneling
                    Fcfxtm: Mucking
                    Fcfxts: Shielding (Tunneling)
        Fcv: Construction of specific vehicles
            Fcvs: Shipbuilding
                Fcvsc: Ship conversion
                Fcvsf: Fairing lines
                Fcvsm: Launching
        Fcy: Construction management
            Fcyc: Construction scheduling
            Fcyh: Design build construction
            Fcyq: Quality control
    Fm: Maintenance
        Fmb: Maintenance practices
            Fmbb: Cleaning
                Fmbbc: Blast cleaning
                Fmbbe: Dust control
                Fmbbf: Flushing
                Fmbbh: Hydraulic jetting
                Fmbbp: Purification
                Fmbbw: Washing
            Fmbk: Rehabilitation (Maintenance)
            Fmbm: Retrofitting
            Fmbn: Reconstruction
            Fmbp: Strengthening (Maintenance)
                Fmbpj: Jacketing (Strengthening)
            Fmbr: Repairing
            Fmbs: Snow and ice control
                Fmbsb: Anti-icing
                Fmbsd: Deicing
                Fmbss: Snow removal
            Fmbw: Winter maintenance
        Fmm: Special maintenance systems
            Fmmd: Deferred maintenance
            Fmmm: Maintenance management
                Fmmmb: Bridge management systems
                Fmmmp: Pavement management systems
            Fmmp: Preventive maintenance
            Fmmz: Zero maintenance systems
        Fmu: Maintenance of specific facilities
            Fmuh: Highway maintenance
                Fmuhp: Pavement maintenance
                    Fmuhpc: Crack and seat treatment
                    Fmuhpf: Full-depth reclamation
                    Fmuhpi: In-place recycling
                        Fmuhpic: Cold in-place recycling
                        Fmuhpih: Hot in-place recycling
                    Fmuhpm: Mudjacking
                    Fmuhpp: Patching
                    Fmuhpr: Resurfacing
                Fmuhs: Street cleaning
            Fmuk: Landscape maintenance
                Fmukf: Fertilization (Horticulture)
                Fmukm: Mowing
                Fmuko: Plant diseases
                Fmukp: Pest control
                    Fmukpa: Aerial application
                    Fmukpb: Biological control
                Fmukt: Vegetation control
                    Fmuktb: Brush control
                    Fmuktw: Weed control
                Fmukv: Watering
                    Fmukvj: Irrigation
            Fmun: Maintenance of way
                Fmung: Rail grinding
                Fmunm: Rail lubrication
        Fmv: Vehicle maintenance
            Fmve: Engine tuning
                Fmvev: Valve timing
            Fmvm: Lubrication
                Fmvmo: Oil changing
            Fmvr: Refueling
        Fmw: Installation
        Fmx: Equipment maintenance
            Fmxp: Pressurization
            Fmxt: Troubleshooting
        Fmy: Equipment replacement
G: Testing
    Gb: Tests
        Gbb: Tests specific to a material, structure or device
            Gbbc: Emissions testing
            Gbbe: Equipment tests
                Gbbef: Diagnostic tests
                    Gbbefe: Fault location
                Gbbej: Impulse tests
                Gbbeq: Shakedown tests
                Gbber: Self diagnostic routines
                Gbbes: Stress tests (Equipment)
                Gbbev: Validation
            Gbbm: Materials tests
                Gbbmb: Aggregate tests
                    Gbbmbc: Aggregate gradation
                        Gbbmbcg: Gap grading
                    Gbbmbp: Polished stone value test
                    Gbbmbs: Sand equivalent test
                    Gbbmbu: Sodium sulfate test
                    Gbbmbw: Tube suction test
                Gbbmd: Asphalt tests
                    Gbbmdh: Hveem test
                    Gbbmdm: Marshall test
                Gbbmk: Concrete tests
                    Gbbmkc: Consistency tests
                    Gbbmkp: Pull out test
                    Gbbmks: Slump test
                    Gbbmku: Soundness test
                Gbbmm: Metal tests
                    Gbbmmn: Notch tests
                Gbbmr: Soil tests
                    Gbbmrj: Index tests
                    Gbbmrm: Plate bearing test
                    Gbbmrp: Shaking table test
                    Gbbmrq: Shear tests
                        Gbbmrqd: Direct shear tests
                        Gbbmrqt: Triaxial shear tests
                        Gbbmrqu: Undrained shear tests
                        Gbbmrqv: Vane shear tests
                    Gbbmrs: Soil compaction test
                    Gbbmrt: Soil consolidation test
                    Gbbmru: Soil penetration test
                        Gbbmrud: Dynamic penetration test
                        Gbbmrus: Static penetration test
                Gbbmt: Soil cement tests
                    Gbbmtw: Wetting and drying tests
            Gbbs: Structural tests
            Gbbv: Vehicle tests
                Gbbvf: Flight tests
                Gbbvr: Road tests
                Gbbvs: Ship trials
                    Gbbvsp: Open water tests
                        Gbbvspy: Zig zag tests
        Gbc: Chemical tests
            Gbcc: Chemical analysis
                Gbcca: Activation analysis
                    Gbccan: Neutron activation analysis
                Gbccb: Bioassay
                Gbccc: Chromatography
                    Gbcccd: Gas chromatography
                    Gbcccg: Gel permeation chromatography
                    Gbcccj: Ion exchange chromatography
                    Gbcccm: Liquid chromatography
                Gbccg: Gas analysis
                Gbccm: Gravimetric analysis
                    Gbccmt: Thermogravimetric analysis
                Gbccn: Infrared analysis
                Gbccp: Microanalysis
                Gbccq: Qualitative analysis
                Gbccr: Quantitative analysis
                Gbccs: Radiometric analysis
                Gbcct: Spectrochemical analysis
                    Gbcctf: Flame photometry
                    Gbcctm: Mass spectrometry
                Gbccu: Thermal analysis
                    Gbccud: Differential thermal analysis
                Gbccv: Trace analysis
                Gbccw: Volumetric analysis
                Gbccx: X ray analysis
            Gbcf: Corrosion tests
                Gbcfs: Salt fog tests
            Gbcq: Flammability tests
            Gbcs: Immersion tests
        Gbg: Mechanical tests
            Gbgb: Bend tests
            Gbgd: Compression tests
            Gbgf: Creep tests
            Gbgh: Fatigue tests
            Gbgj: Fracture tests
            Gbgl: Hardness tests
                Gbglm: Mohs scale
            Gbgn: Impact tests
                Gbgnd: Drop tests
                Gbgnp: Pendulum tests
            Gbgp: Load tests
                Gbgpb: Bearing tests
                Gbgpd: Deflection tests
                Gbgps: Stiffness tests
            Gbgr: Pumping tests
            Gbgt: Relaxation tests
            Gbgu: Spiral flow tests
            Gbgv: Tension tests
                Gbgvd: Ductility tests
                Gbgvr: Resistance tests
            Gbgw: Torsion tests
            Gbgx: Vibration tests
        Gbh: Nondestructive tests
            Gbhb: Acoustic emission tests
            Gbhn: Nuclear tests
            Gbhs: Sonic tests
            Gbhu: Ultrasonic tests
        Gbj: Tests for suitability, service and quality
            Gbjb: Acceptance tests
            Gbjd: Durability tests
                Gbjdn: Temperature endurance tests
                    Gbjdnf: Freeze thaw tests
                    Gbjdnm: Low temperature tests
                    Gbjdnp: Oven tests
            Gbjm: Leak tests
            Gbjp: Performance tests
            Gbjs: Prototype tests
            Gbju: Sieve analysis
        Gbk: Surface texture tests
            Gbkb: Abrasion tests
            Gbkf: Friction tests
            Gbks: Skid resistance tests
        Gbm: Weld tests
        Gbp: Tests by cycle
            Gbpd: Accelerated tests
            Gbpf: Cyclic tests
        Gbs: Static and dynamic tests
            Gbsd: Dynamic tests
            Gbss: Static tests
        Gbw: Tests by location
            Gbwf: Field tests
            Gbwm: Laboratory tests
    Ge: Structural analysis
        Geb: Dynamic structural analysis
            Gebm: Modal analysis
        Gee: Elastic analysis
        Gef: Equilibrium methods (Structural analysis)
        Geh: Failure analysis
        Gej: Finite element method
        Gek: Mohr circles
        Gem: Plastic analysis
        Geq: Stability analysis
            Geqm: Method of slices
        Get: Static structural analysis
        Gev: Strut and tie method
        Gey: Yield line method
    Gm: Measurement
        Gmc: Measurement of specific phenomena
            Gmce: Measurement of electromagnetic phenomena
                Gmceh: Harmonic analysis (Physics)
                Gmcep: Optical measurement
                    Gmcepc: Colorimetry
                    Gmcepp: Photometry
                Gmcer: Radiometry
                Gmces: Spectroscopic analysis
                    Gmcesb: Absorption spectroscopy
                        Gmcesbu: Ultraviolet spectroscopy
                    Gmcesf: Infrared spectroscopy
                    Gmcesg: Spectrographic analysis
                    Gmcesp: Spectrophotometry
                Gmceu: Spectrum analysis
                Gmcex: Waveform analysis
            Gmcg: Flow measurement
            Gmck: Strain measurement
            Gmcn: Temperature measurement
            Gmcp: Velocity measurement
                Gmcps: Speed measurement
            Gmcs: Wave measurement
            Gmcw: Weight measurement
        Gmm: Measuring methods
            Gmmd: Dimensional analysis
            Gmme: Electrical measurement
            Gmmg: Empirical methods
            Gmms: Sounding
            Gmmv: Vacuum measurement
        Gms: Values in measurement
            Gmsa: Azimuth
            Gmsb: Base lines
            Gmsc: Benchmarks
            Gmsd: Constants
            Gmse: Calibration
            Gmsf: Coordinates
            Gmsg: Gage (Rails)
            Gmsh: Accuracy
            Gmsk: Errors
            Gmsm: Magnitude
                Gmsmp: Precision
            Gmso: Metrics (Quantitative assessment)
            Gmsq: Quanta
            Gmsu: Uncertainty
            Gmsw: Weighting
        Gmy: Systems of measurement
            Gmym: Metric system
            Gmyr: Imperial system of units
            Gmyu: U.S. customary system of units
    Gn: Investigation of structure
        Gnk: Metallography
        Gnm: Microscopy
    Gr: Inspection
        Grc: Condition surveys
        Grf: Flaw detection
        Gry: Inspection equipment
            Grys: Smart pigs
    Gs: Experiments
    Gt: Sampling
        Gtc: Acceptance sampling
    Gu: Testing equipment
        Gub: Automatic test equipment
        Guc: Centrifuges
        Gug: Gyratory testing machines
        Guk: Indicating instruments
            Gukc: Clocks
            Gukp: Odometers
            Guks: Speed indicators
                Gukss: Speedometers
            Gukw: Weight indicators
        Gum: Measuring instruments
            Gume: Measuring instruments by technique
                Gumeb: Acoustic measuring instruments
                Gumec: Cells (Measuring devices)
                    Gumecm: Load cells
                Gumek: Micrometers
                Gumen: Nuclear gages
                    Gumend: Nuclear density gages
                    Gumenm: Nuclear moisture gages
                    Gumenp: Nuclear probes
                Gumep: Optical instruments
                    Gumepr: Reflectometers
                Gumes: Probes (Measuring devices)
                    Gumesn: Nuclear probes
                    Gumesp: Pressiometric probes
            Gump: Instruments for measuring specific phenomena
                Gumpa: Accelerometers
                    Gumpab: Accelerographs
                Gumpb: Altimeters
                Gumpc: Calorimeters
                Gumpd: Instruments for measuring electricity
                    Gumpdc: Circuit analyzers
                    Gumpde: Electric meters
                    Gumpdg: Galvanometers
                        Gumpdgg: Galvanic skin response
                    Gumpdn: Noise generators
                    Gumpdp: Oscilloscopes
                    Gumpdt: Transient analyzers
                    Gumpdv: Voltmeters
                Gumpf: Instruments for measuring electromagnetic phenomena
                    Gumpff: Frequency analyzers
                    Gumpfj: Interferometers
                    Gumpfm: Magnetometers
                    Gumpfp: Photometers
                    Gumpfq: Radiometers
                    Gumpfr: Signal generators
                    Gumpfs: Spectrometers
                        Gumpfss: Satellite infrared spectrometers
                    Gumpft: Spectrophotometers
                    Gumpfv: Time domain reflectometers
                    Gumpfw: Wavemeters
                Gumph: Instruments for measuring expansion
                    Gumphd: Dilatometers
                Gumpj: Flowmeters
                Gumpm: Fluorometers
                Gumpn: Gravimeters
                Gumpp: Instruments for measuring loads or pressure
                    Gumppb: Barometers
                    Gumppe: Load cells
                    Gumpph: Loadometers
                    Gumppi: Oedometers
                    Gumppj: Piezometers
                    Gumppn: Pitot tubes
                    Gumppr: Pressiometric probes
                    Gumpps: Pressure gages
                    Gumppt: Pressure transducers
                    Gumppv: Strain gages
                Gumpq: Sound level meters
                Gumpr: Instruments for measuring power
                    Gumprd: Dynamometers
                    Gumprp: Potentiometers
                Gumps: Seismometers
                Gumpt: Instruments for measuring speed or velocity
                    Gumptb: Anemometers
                    Gumpts: Speedometers
                    Gumptt: Tachometers
                    Gumptv: Velocimeters
                        Gumptvm: Laser velocimeters
                            Gumptvmd: Laser doppler velocimeters
                Gumpv: Stress gages
                Gumpw: Instruments for measuring time
                    Gumpwc: Chronometers
                    Gumpwe: Clocks
                Gumpy: Vibrometers
            Gums: Instruments for measuring specific properties
                Gumsb: Instruments for measuring chemical content or structure
                    Gumsbh: Hygrometers
                    Gumsbm: Mass spectroscopes
                        Gumsbmm: Mass spectrometers
                    Gumsbn: Moisture meters
                    Gumsbp: Nuclear moisture gages
                Gumsd: Instruments for measuring consistency
                    Gumsdc: Consolidometers
                    Gumsdp: Penetrometers
                        Gumsdpc: Cone penetrometers
                Gumsj: Instruments for measuring deformation or deflection
                    Gumsjb: Benkelman beam
                    Gumsjd: Deflectometers
                        Gumsjdf: Falling weight deflectometers
                    Gumsje: Dynaflect
                    Gumsjg: Extensometers
                    Gumsjj: Inclinometers
                    Gumsjr: Road raters
                Gumsm: Instruments for measuring density
                    Gumsmd: Densitometers
                    Gumsmn: Nuclear density gages
                Gumsp: Porosimeters
                Gumsr: Instruments for measuring roughness
                    Gumsrp: Profilometers
                    Gumsrr: Road meters
                Gumss: Sizing apparatus
                    Gumsss: Sieves
                Gumst: Instruments for measuring the strength of asphalt
                    Gumstc: Hveem cohesiometer
                    Gumsts: Hveem stabilometer
                Gumsv: Temperature measuring instruments
                    Gumsvc: Thermocouples
                    Gumsvm: Thermometers
                    Gumsvs: Thermostats
                Gumsx: Viscometers
                Gumsy: Weighing devices
            Gumt: Surveying instruments
                Gumts: Theodolites
            Gumu: Meteorological instruments
                Gumub: Anemometers
                Gumuf: Barometers
                Gumum: Hygrometers
                Gumun: Psychrometers
                Gumur: Rain gages
            Gumy: Instruments for measuring fluid properties or phenomena
                Gumyd: Dilatometers
                Gumyf: Flowmeters
                Gumyh: Hydrometers
                Gumyn: Permeameters
                Gumyp: Pitot tubes
                Gumyq: Pressure transducers
                Gumyr: Psychrometers
                Gumys: Stream gages
                Gumyt: Tensiometers
                Gumyv: Viscometers
        Gup: Microscopes
            Gupe: Electron microscopes
        Gur: Recording instruments
            Gurd: Deflectographs
            Gurp: Oscillographs
            Gurq: Profilographs
            Gurs: Seismographs
            Gurt: Tachographs
            Gurv: Thermographs
        Gus: Samplers
            Gusq: Soil samplers
        Gut: Spectrum analyzers
        Guu: Test piles
        Gux: Test stands
            Guxt: Test beds
    Gv: Samples, specimens and test holes
        Gvm: Samples
            Gvmd: Disturbed samples
            Gvmu: Undisturbed samples
            Gvmx: Representative samples (Testing)
        Gvp: Specimens
            Gvpc: Cores (Specimens)
        Gvt: Test holes
            Gvtb: Boreholes
            Gvtm: Logging (Recording)
    Gw: Structural models
        Gwp: Prototypes
        Gws: Scale models
    Gy: Test procedures
H: Safety and security
    Ha: Safety
        Haa: Transportation safety
            Haaa: Aviation safety
            Haam: Marine safety
                Haamm: Maritime safety
            Haap: Pipeline safety
            Haar: Railroad safety
            Haat: Traffic safety
                Haath: Highway safety
                    Haathw: Work zone safety
                Haatk: Trucking safety
            Haau: Transit safety
            Haav: Vehicle safety
                Haava: Escape systems
                Haavf: Fleet safety
                Haavr: Recall campaigns
                Haavs: Vehicle fitness
                    Haavsf: Airworthiness
                    Haavsg: Crashworthiness
                    Haavsh: Seaworthiness
            Haaw: Pedestrian safety
        Hac: Construction safety
        Hap: Product safety
        Haq: Occupational safety
        Har: School safety
            Harp: School patrols
        Has: Safety factors
            Hasm: Legibility
            Hasv: Visibility
                Hasvd: Visibility distance
                Hasvn: Night visibility
        Hau: Safety engineering
            Hauf: Fail safe systems
            Haus: System safety
        Haw: Safety programs
            Hawa: Safety audits
            Hawc: Safety campaigns
            Hawm: Safety management
            Hawp: Safety propaganda
            Hawt: Safety education
                Hawtt: Traffic safety education
                    Hawttd: Driver education
                        Hawttdb: High school driving courses
                        Hawttdc: Classroom driver instruction
                        Hawttdt: Driver training
                        Hawttdu: Driver rehabilitation
                        Hawttdv: Driver improvement programs
                    Hawttp: Pedestrian education
        Hax: Countermeasures
        Hay: Risk assessment
    Hb: Accidents
        Hbb: Accident types
            Hbba: Aircraft accidents
                Hbbac: Aircraft collisions
                    Hbbacm: Midair collisions
                    Hbbacn: Near midair collisions
                Hbbar: Runway incursions
                Hbbat: Runway overruns
            Hbbg: Ground transportation accidents
                Hbbgb: Bicycle accidents
                Hbbgc: Bus accidents
                Hbbgk: Moped accidents
                Hbbgm: Motorcycle accidents
                Hbbgp: Pedestrian accidents
                Hbbgr: Railroad accidents
                    Hbbgrd: Derailments
                Hbbgt: Traffic accidents
                    Hbbgta: Single vehicle accidents
                        Hbbgtah: Hit and run accidents
                        Hbbgtaj: Ran off road accidents
                        Hbbgtat: Rollover accidents
                    Hbbgtb: Multiple vehicle accidents
                    Hbbgtc: Collisions
                        Hbbgtch: Head on collisions
                        Hbbgtcr: Rear end collisions
                        Hbbgtcs: Side collisions
                            Hbbgtcsa: Right angle collisions
                        Hbbgtcu: Underride override collisions
                        Hbbgtcw: Secondary collisions
                Hbbgu: Truck accidents
                    Hbbguj: Jackknifing
                Hbbgw: Transit accidents
            Hbbm: Maritime accidents
                Hbbma: Shipwrecks
                Hbbmc: Ship collisions
                    Hbbmcb: Allisions
                Hbbmd: Groundings (Maritime accidents)
                Hbbmt: Capsizing
            Hbbs: Industrial accidents
            Hbbw: Falls
        Hbc: Accident causes
            Hbch: Human factors in accidents
                Hbche: Driver errors
                    Hbchee: Speeding
                    Hbcheg: Oversteer
                    Hbcheh: Understeer
                    Hbcheq: Loss of control
                    Hbchew: Wrong way driving
                Hbchg: Driver experience
                Hbchp: Accident proneness
                Hbchr: Accident exposure
                Hbchs: Sleep deprivation
            Hbcv: Vehicle factors in accidents
                Hbcvh: Hydroplaning
                Hbcvs: Skidding
            Hbcw: Highway factors in accidents
        Hbk: Accident characteristics
            Hbkd: Accident severity
            Hbkg: Accident locations
                Hbkga: Accident prone locations
                    Hbkgar: Roadside hazards
            Hbkt: Time of accidents
                Hbktd: Daytime accidents
                Hbktn: Nighttime accidents
        Hbp: Crash phases
            Hbpb: Precrash phase
            Hbpk: Crash phase
                Hbpkc: Occupant vehicle interface
                    Hbpkcd: Occupant dynamics
                        Hbpkcde: Ejection
                    Hbpkcn: Occupant kinetics
                Hbpkt: Vehicle trajectories
            Hbpp: Postcrash phase
                Hbppd: Debris removal
                Hbpps: Survival
                    Hbppst: Accident survival time
        Hbw: Accident analysis
        Hbx: Accident investigation
            Hbxb: On the scene accident investigation
                Hbxbb: Accident investigation sites
                    Hbxbbs: Skidmarks
            Hbxf: Follow up investigation
            Hbxr: Accident reconstruction
                Hbxrd: Accident diagrams
                    Hbxrdc: Collision diagrams
            Hbxx: Accident data
                Hbxxk: Trilevel accident investigation
                Hbxxr: Accident records
                    Hbxxrr: Accident reports
                Hbxxs: Accident rates
                    Hbxxsv: Accident risk forecasting
    Hh: Hazards and emergency operations
        Hhd: Hazards
            Hhda: Hazard analysis
            Hhde: Hazard evaluation
            Hhdg: Hazard mitigation
            Hhdh: Health hazards
            Hhdm: Hazard markings
        Hhg: Disasters and emergency operations
            Hhgd: Disasters
                Hhgdb: Disaster preparedness
                Hhgdr: Disaster relief
            Hhge: Emergencies
                Hhgec: Emergency communication systems
                Hhgem: Emergency management
            Hhgm: Lifelines
            Hhgr: Search and rescue operations
                Hhgrm: Lifesaving
                Hhgrp: Vehicle occupant rescue
                Hhgrt: Emergency response time
            Hhgv: Evacuation
        Hhr: Radiation hazards
            Hhrd: Radiation doses
            Hhrm: Radiation monitoring
            Hhrs: Radiation shielding
        Hhu: Fires
            Hhua: Fire causes
            Hhud: Fire detection systems
            Hhuf: Fire fighting
            Hhup: Fire prevention
            Hhuy: Fires by type
                Hhuyf: Forest fires
                Hhuyv: Vehicle fires
        Hhw: Warning systems
    Hj: Injuries
        Hjb: Injury classification
        Hjc: Injury causes
            Hjcc: Crash injuries
        Hjh: Injury characteristics
            Hjhc: Casualties
            Hjhm: Multiple injuries
            Hjhr: Injury rates
            Hjhs: Injury severity
            Hjhx: Fatalities
                Hjhxr: Road kill
        Hjp: Injury types
            Hjpb: Skin injuries
                Hjpbb: Abrasions
                Hjpbc: Contusions
                Hjpbf: Laceration
                Hjpbr: Avulsions
            Hjpc: Amputations
            Hjpd: Fractures (Anatomy)
                Hjpds: Skull fractures
            Hjpe: Dislocations
                Hjpew: Whiplash
            Hjpf: Burns (Injuries)
            Hjpg: Crushing injuries
            Hjpm: Open wounds
            Hjpp: Penetrating injuries
            Hjpv: Internal injuries
            Hjpw: Bleeding
            Hjpy: Pathological processes
                Hjpya: Asphyxia
                    Hjpyah: Drowning
                Hjpyh: Hypothermia
        Hjr: Crash injury research
            Hjrc: Impact tests
                Hjrcs: Sled tests
            Hjrs: Crash victim simulation
                Hjrsb: Dummies
    Hm: Pathology
        Hmd: Diseases and medical conditions
            Hmdb: Cardiovascular diseases
                Hmdbc: Apnea
                Hmdbh: Cardiac disorder
                Hmdbs: Shock (Pathology)
                Hmdbv: Hypertension
            Hmdc: Occupational diseases
            Hmdd: Communicable diseases
            Hmde: Ear diseases
                Hmdem: Motion sickness
            Hmdf: Cancer
            Hmdg: Glandular diseases
                Hmdgd: Diabetes
                Hmdgo: Obesity
            Hmdh: Hypoxia
            Hmdn: Nervous system diseases
                Hmdne: Epilepsy
                Hmdnn: Narcolepsy
            Hmdq: Drug use
                Hmdqb: Drug abuse
                Hmdqc: Drug addiction
                Hmdqe: Drug effects
                Hmdqs: Smoking
                Hmdqx: Drugs
                    Hmdqxa: Types of drugs
                    Hmdqxd: Narcotics
                        Hmdqxdb: Barbiturates
                        Hmdqxdh: Heroin
                    Hmdqxh: Hallucinogenic drugs
                    Hmdqxm: Marijuana
                    Hmdqxs: Stimulants
                        Hmdqxsc: Caffeine
                        Hmdqxsh: Amphetamines
                        Hmdqxsk: Cocaine
            Hmds: Alcohol use
                Hmdsa: Legal drinking age
                Hmdsb: Alcohol abuse
                Hmdsd: Alcoholism
                Hmdse: Alcohol effects
                    Hmdsed: Intoxication
                        Hmdsedd: Drunk driving
                            Hmdseddy: Zero tolerance
                    Hmdseh: Hangover
                Hmdsu: Alcoholic beverages
                Hmdsx: Drinking establishments
        Hme: Poisoning
            Hmec: Catalyst poisoning
        Hmx: Pathological data
            Hmxp: Epidemiology
            Hmxt: Etiology
    Hp: Medical services
        Hpa: Health care
        Hpe: Emergency medical services
            Hpea: First aid
            Hper: Resuscitation
        Hpg: Medical treatment
            Hpgf: Anesthesia
            Hpgh: Life support systems
            Hpgk: Surgery
            Hpgm: Medication
                Hpgmd: Dosage
                Hpgmh: Antihistamines
                Hpgmp: Psychotropic agents
                Hpgms: Sedatives
                Hpgmt: Tranquilizers
                Hpgmu: Antidepressants
                Hpgmx: Placebos
            Hpgt: Therapy
                Hpgtb: Behavior modification
                Hpgtp: Psychotherapy
            Hpgv: Outcome (Medical treatment)
        Hpm: Medical examinations and tests
            Hpmb: Blood analysis
                Hpmba: Blood alcohol levels
                Hpmbc: Blood carbon monoxide levels
            Hpmc: Cadavers
            Hpme: Electroencephalography
            Hpmk: Electrocardiography
            Hpmp: Urinalysis
                Hpmpa: Urine alcohol levels
            Hpmt: Drug tests
            Hpmw: Alcohol tests
                Hpmwb: Alcohol blood tests
                Hpmwd: Alcohol breath tests
                    Hpmwdr: Random breath tests
                Hpmwg: Alcohol chemical tests
            Hpmx: Autopsies
            Hpmy: Disability evaluation
        Hpx: Medical records
            Hpxc: Medical case reports
    Hr: Law enforcement
        Hra: Automated enforcement
        Hrb: Police powers
            Hrbc: Custody
            Hrbe: Entrapment
            Hrbs: Search and seizure
        Hrk: Police operations
            Hrkb: Warnings (Police operations)
            Hrkf: Warrants (Police operations)
            Hrkg: Interrogation
            Hrkj: Police pursuit driving
            Hrkk: Arrests
            Hrkp: Police patrol
            Hrkr: Roadblocks
            Hrkt: Police traffic services
                Hrktb: Traffic patrol
                Hrktc: Sobriety checkpoints
                Hrkte: Traffic law enforcement
                    Hrktec: Traffic citations
                    Hrktek: Traffic arrests
                    Hrkteq: Traffic conviction
                Hrktg: Police traffic direction
                Hrktm: Police motorist contacts
                Hrktt: Traffic ticket systems
                    Hrkttd: Point demerit systems
        Hrp: Prosecution
        Hrx: Police reports
    Hs: Security
        Hsa: Prevention
        Hsb: Protection
        Hsc: Security checkpoints
        Hsf: Freight security
        Hsp: Passenger security
        Hsu: False alarms (Security)
        Hsw: National security
            Hswd: National defense
            Hswe: Defense
                Hswec: Civil defense
    Hu: Crimes
        Hub: Violent crimes
            Hubh: Homicide
                Hubha: Vehicular homicide
            Hubs: Suicide
                Hubsa: Vehicular suicide
        Hud: Property crimes
            Hudb: Theft
            Huds: Sabotage
            Hudv: Vandalism
                Hudvg: Graffiti
        Huf: Fraud
        Huh: Terrorism
            Huhc: Bombings
        Hus: Smuggling
            Husd: Drug smuggling
        Hut: Crimes involving transportation
            Huta: Vehicle theft
            Hute: Crimes aboard public vehicles
                Huted: Crimes aboard aircraft
                Hutef: Crimes aboard buses
            Huth: Hijacking
                Huthc: Carjacking
                Huthf: Skyjacking
            Hutp: Piracy
            Huts: Smuggling
        Huv: Traffic violations
            Huvm: Moving violations
                Huvmd: Driving without a license
                Huvmr: Red light running
            Huvp: Parking violations
        Huw: Threats
        Hux: Negligence
    Hv: Criminal histories
        Hvr: Recidivism
    Hw: Loss and damage
        Hwb: Losses
J: Environment
    Jb: Environmental phenomena
        Jbb: Astronomical phenomena
            Jbbe: Earth movements (Geophysics)
            Jbbg: Gravity
            Jbbs: Surface friction (Geophysics)
            Jbbt: Tides
                Jbbtp: Ocean tides
                    Jbbtpc: Tidal currents
        Jbc: Outer space
        Jbd: Celestial bodies
            Jbde: Earth
            Jbdm: Moon
            Jbds: Sun
        Jbg: Geological phenomena
            Jbge: Geological events
                Jbgee: Earthquakes
                Jbgem: Landslides
                    Jbgemc: Debris flows
                        Jbgemcb: Debris avalanches
                        Jbgemcs: Debris slides
                    Jbgemf: Earthflows
                    Jbgemm: Mudflows
                        Jbgemmm: Mudslides
                    Jbgemq: Rockfalls
                    Jbgemr: Rockslides
                    Jbgemt: Rotational landslides
                    Jbgemu: Translational landslides
                Jbgev: Volcanic eruptions
            Jbgp: Geological activities and processes
                Jbgpb: Consolidation
                Jbgpc: Deposition
                    Jbgpcs: Stratification
                    Jbgpcu: Superposition (Geology)
                Jbgpd: Dislocation (Geology)
                Jbgpe: Erosion
                    Jbgpew: Wind erosion
                Jbgpf: Faulting
                Jbgph: Frost action
                Jbgpj: Injection (Geology)
                Jbgpm: Rebound
                Jbgpr: Sand blasting
                Jbgps: Sedimentation
                Jbgpt: Seismicity
                Jbgpu: Subsidence (Geology)
                Jbgpw: Ground settlement
                Jbgpx: Slope stability
                    Jbgpxf: Slope failure
                Jbgpy: Submergence (Geology)
            Jbgy: Geologically affected surfaces
                Jbgyf: Faults
                Jbgyg: Grabens
                Jbgyi: Karst
                Jbgyk: Potholes (Geology)
                Jbgyp: Rupture surfaces
                Jbgyr: Shear zones
                    Jbgyrr: Ring stress
                Jbgyt: Sinkholes
                Jbgyv: Slip surfaces
                Jbgyx: Troughs (Geology)
        Jbh: Hydrologic phenomena
            Jbha: Aggressive waters
            Jbhb: Degradation (Hydrology)
            Jbhc: Desiccation
            Jbhd: Drainage
                Jbhdb: Subsurface drainage
                Jbhdr: Surface drainage
            Jbhf: Floods
                Jbhfd: Design flood
            Jbhh: Hydrologic cycle
            Jbhi: Streamflow
            Jbhl: River currents
            Jbhm: Ocean currents
                Jbhms: Sinking (Oceanography)
            Jbhn: Peak discharge
                Jbhnr: Rational formula (Hydraulics)
            Jbho: Ponding
            Jbhp: Runoff
            Jbhr: Sediment discharge
            Jbhs: Seepage
            Jbht: Storm surges
            Jbhu: Upwelling
            Jbhv: Water table
                Jbhvd: Drawdown (Hydraulics)
                Jbhvr: Groundwater recharge
            Jbhw: Water waves
                Jbhwf: Following seas
                Jbhwp: Ocean waves
                    Jbhwps: Surf
                    Jbhwpu: Tidal waves
                    Jbhwpx: Tsunamis
                Jbhww: Wind waves
                Jbhwy: Properties of water waves
                    Jbhwys: Wave height
            Jbhx: Sea level
            Jbhy: Phenomena of frozen water
                Jbhyb: Avalanches
                Jbhyf: Frost
                Jbhyj: Ice phenomena
                    Jbhyjj: Ice formations
                        Jbhyjjd: Drift ice
                        Jbhyjjf: Ice floes
                        Jbhyjjj: Ice islands
                        Jbhyjjm: Icebergs
                        Jbhyjjp: Glaciers
                        Jbhyjjs: Icing
                            Jbhyjjsb: Black ice
                            Jbhyjjsj: Icy roads
                    Jbhyjp: Ice by location
                        Jbhyjpm: Lake ice
                        Jbhyjpr: River ice
                        Jbhyjps: Sea ice
                            Jbhyjpsp: Pack ice
                    Jbhyjs: Ice concentration
                Jbhys: Snow phenomena
                    Jbhysc: Snow cover
                    Jbhysd: Snowdrifts
                    Jbhysm: Snowmelt
        Jbm: Meteorological phenomena
            Jbmb: Atmosphere
                Jbmba: Atmospheric layers
                    Jbmbac: Troposphere
                    Jbmbag: Stratosphere
                    Jbmbam: Mesosphere
                    Jbmbaq: Ionosphere
                    Jbmbav: Exosphere
                    Jbmbay: Special subdivisions of the atmosphere
                        Jbmbayb: Airspace (Aeronautics)
                        Jbmbaym: Airspace (Law)
                Jbmbb: Properties of the atmosphere
                    Jbmbbp: Atmospheric pressure
                        Jbmbbpf: Pressure fields
                        Jbmbbpw: Pressure waves
                    Jbmbbt: Atmospheric temperature
                    Jbmbbx: Humidity
                Jbmbk: Atmospheric phenomena
                    Jbmbkd: Atmospheric circulation
                    Jbmbkg: Atmospheric diffusion
                    Jbmbkj: Atmospheric turbulence
                        Jbmbkjc: Clear air turbulence
                    Jbmbkk: Haze
                    Jbmbkl: Lightning
                    Jbmbkm: Water in the atmosphere
                        Jbmbkmb: Atmospheric water vapor
                            Jbmbkmbc: Clouds
                            Jbmbkmbf: Fog
                                Jbmbkmbfj: Ice fog
                        Jbmbkmp: Precipitation (Meteorology)
                            Jbmbkmpr: Rain
                                Jbmbkmprr: Rainfall
                            Jbmbkmps: Snow
                                Jbmbkmpss: Snowfall
                    Jbmbkp: Atmospheric pressure phenomena
                        Jbmbkpc: Cyclones
                            Jbmbkpch: Hurricanes
                            Jbmbkpct: Typhoons
                        Jbmbkpf: Fronts (Meteorology)
                        Jbmbkps: Storms
                            Jbmbkpsd: Design storm
                            Jbmbkpsj: Ice storms
                            Jbmbkpsq: Snowstorms
                            Jbmbkpst: Thunderstorms
                    Jbmbks: Heat storage
                    Jbmbkw: Wind
                        Jbmbkwb: Air currents
                            Jbmbkwbd: Downdrafts
                                Jbmbkwbdm: Microbursts
                        Jbmbkwc: Crosswinds
                        Jbmbkwg: Gusts
                        Jbmbkwj: Jet stream
                        Jbmbkwt: Tornadoes
                        Jbmbkww: Wind shear
                            Jbmbkwwv: Vertical wind shear
                Jbmby: Model atmosphere
            Jbmw: Weather and climate
                Jbmwb: Weather
                    Jbmwbb: Weather conditions
                        Jbmwbbc: Cold weather
                        Jbmwbbd: Dry weather
                        Jbmwbbh: Hot weather
                        Jbmwbbw: Wet weather
                        Jbmwbby: Thaw
                    Jbmwbf: Weather forecasting
                Jbmwn: Climate
                    Jbmwnc: Climate change
                    Jbmwnd: Drought
                    Jbmwnw: Global warming
        Jby: Deterioration by environmental action
            Jbyb: Biodeterioration
            Jbyd: Fouling (Naval architecture)
            Jbye: Flood damage
            Jbyf: Frost damage
                Jbyfh: Frost heaving
            Jbym: Moisture damage
            Jbyn: Scour
            Jbyp: Settlement (Structures)
                Jbypd: Differential settlement
            Jbyq: Silting
            Jbyt: Thermal degradation
            Jbyy: Weathering
                Jbyyc: Accelerated weathering
    Jc: Living things
        Jca: Cells (Biology)
            Jcan: Nucleus (Biology)
        Jcb: Classes of living things
            Jcbp: Plants
                Jcbpc: Algae
                Jcbpg: Bacteria
                Jcbpk: Fungi
                Jcbpp: Grasses
                Jcbpq: Ground cover
                Jcbps: Shrubs
                Jcbpv: Trees
                Jcbpy: Parts of plants
                    Jcbpyr: Roots
                    Jcbpys: Seeds
            Jcbt: Animals
                Jcbtj: Invertebrates
                    Jcbtjc: Crustacea
                        Jcbtjcb: Barnacles
                        Jcbtjcs: Shrimp
                    Jcbtjj: Insects
                        Jcbtjjm: Larvae
                        Jcbtjjt: Termites
                    Jcbtjm: Mollusca
                Jcbtv: Vertebrates
                    Jcbtvb: Fishes
                        Jcbtvbt: Salmon
                    Jcbtvd: Amphibians
                        Jcbtvdf: Frogs (Amphibians)
                    Jcbtvf: Birds
                    Jcbtvu: Mammals
                        Jcbtvuc: Carnivores
                            Jcbtvucb: Cats
                            Jcbtvucd: Dogs
                        Jcbtvup: Primates
                            Jcbtvupb: Baboons
                            Jcbtvuph: Human beings
                            Jcbtvupm: Monkeys
                        Jcbtvur: Rodents
                            Jcbtvurr: Rabbits
                            Jcbtvurs: Rats
                        Jcbtvuu: Ungulates
                            Jcbtvuud: Deer
                            Jcbtvuuh: Horses
        Jcm: Living things by characteristics
            Jcmb: Living things by region
                Jcmbb: Aquatic life
                    Jcmbbb: Benthos
                    Jcmbbp: Plankton
                        Jcmbbpp: Phytoplankton
                        Jcmbbpy: Zooplankton
                    Jcmbbs: Shellfish
                        Jcmbbsc: Crabs
                Jcmbd: Biomass
                    Jcmbdv: Vegetation
                        Jcmbdvn: Native plants
                Jcmbr: Roadside flora and fauna
                    Jcmbrf: Roadside fauna
                    Jcmbrm: Roadside flora
            Jcmf: Laboratory animals
            Jcmk: Undomesticated living things
                Jcmkf: Wildflowers
                Jcmkm: Wildlife
            Jcmp: Living things detrimental to human activity
                Jcmpb: Bird pests
                Jcmpf: Fouling organisms
                Jcmpm: Marine borers
                Jcmpu: Invasive plants
                Jcmpw: Weeds
            Jcmx: Microorganisms
    Jd: Biological activity
        Jdb: Aging (Biology)
        Jde: Evolution
        Jdg: Food chain
        Jdr: Reproduction (Biology)
            Jdrf: Fetus
        Jdt: Animal behavior
            Jdtf: Animal migrations
            Jdtp: Bird strikes
        Jdx: Plant activity
            Jdxe: Evapotranspiration
            Jdxp: Plant growth
                Jdxpp: Primary production
    Je: Ecosystems
        Jeb: Biodiversity
        Jee: Endangered species
        Jeh: Habitat (Ecology)
        Jeq: Stream restoration
        Jes: Synergism (Ecology)
    Jf: Environmental quality
        Jfa: Quality of specific environments
            Jfab: Air quality
            Jfaw: Water quality
        Jfb: Environmental policy
            Jfbc: Coastal zone management
            Jfbs: Environmental streamlining
        Jfc: Environmental protection
        Jfd: Environmental risk assessment
        Jfe: Environmental impacts
            Jfee: Environmental impact analysis
        Jff: Environmental monitoring
        Jfg: Pollution
            Jfgb: Pollution of specific environments
                Jfgbb: Air pollution
                    Jfgbbg: Greenhouse effect
                    Jfgbbs: Smog
                    Jfgbbu: Air pollution sources
                        Jfgbbum: Mobile sources
                        Jfgbbus: Stationary sources
                Jfgbs: Soil pollution
                Jfgbw: Water pollution
                    Jfgbwt: Thermal pollution
                    Jfgbww: Wastewater
            Jfgs: Pollutants
                Jfgsb: Acid rain
                Jfgsc: Contaminants
                Jfgse: Evaporative emissions
                Jfgsf: Fumes
                Jfgsg: Polluting gases
                    Jfgsge: Exhaust gases
                        Jfgsgea: Aircraft exhaust gases
                        Jfgsged: Diesel engine exhaust gases
                    Jfgsgf: Flue gases
                    Jfgsgg: Greenhouse gases
                    Jfgsgs: Stack gases
                Jfgsp: Odors
                Jfgsr: Tobacco smoke
                Jfgss: Spills (Pollution)
                    Jfgssc: Chemical spills
                    Jfgssp: Oil spills
            Jfgt: Intentional polluting actions
                Jfgtm: Misfueling
                Jfgtt: Tampering
            Jfgy: Pollution control
                Jfgyb: Air quality management
                    Jfgybe: Emissions trading
                    Jfgybf: Fuel substitution
                    Jfgybn: Nonattainment areas
                Jfgys: Soil remediation
                Jfgyu: Bioremediation
                Jfgyw: Water quality management
                    Jfgywp: Oil spill cleanup
                    Jfgyws: Sewerage
                        Jfgywsc: Sewage collection
                        Jfgywsm: Sewage treatment
                            Jfgywsmb: Biochemical oxygen demand
                        Jfgywsx: Sewage disposal
        Jfk: Wastes
            Jfkb: Types of wastes
                Jfkbb: Agricultural wastes
                Jfkbe: Effluents
                Jfkbh: Hazardous wastes
                Jfkbj: Industrial wastes
                Jfkbm: Litter
                Jfkbn: Radioactive wastes
                    Jfkbnp: Plumes
                Jfkbp: Refuse
                Jfkbr: Solid wastes
                Jfkbt: Spoil
            Jfky: Waste management
                Jfkyd: Waste disposal
                    Jfkydr: Radioactive waste disposal
                    Jfkyds: Solid waste disposal
                Jfkym: Waste minimization
                Jfkyr: Recycling
                Jfkys: Salvage
                    Jfkysm: Marine salvage
        Jfn: Noise
            Jfnb: Noise sources
                Jfnbb: Aircraft noise
                    Jfnbbb: Airport noise
                Jfnbc: Ambient noise
                Jfnbd: Cavitation noise
                Jfnbt: Traffic noise
                    Jfnbtt: Tire/pavement noise
            Jfny: Noise control
    Jn: Natural resources
        Jna: Specific natural resources
            Jnae: Energy resources
                Jnaeg: Geothermal resources
                Jnaer: Renewable energy sources
            Jnam: Mineral resources
                Jnamc: Coal resources
            Jnaw: Water resources
        Jng: Conservation
            Jnge: Energy conservation
                Jngef: Fuel conservation
            Jngs: Soil conservation
                Jngse: Erosion control
            Jngw: Water conservation
            Jngx: Wetland conservation
        Jnr: Resource development and utilization
            Jnrr: Resource development
                Jnrrb: Resource extraction
                    Jnrrbe: Exploration
                        Jnrrbeg: Geophysical prospecting
                            Jnrrbegr: Resistivity method
                            Jnrrbegs: Seismic prospecting
                        Jnrrbep: Oil exploration
                    Jnrrbk: Logging
                        Jnrrbks: Strip method
                    Jnrrbm: Mining
                        Jnrrbmc: Coal mining
                        Jnrrbmr: Materials recovery (Mining)
                        Jnrrbms: Strip mining
                        Jnrrbmv: Mine haulage
                    Jnrrbp: Oil well drilling
                        Jnrrbph: Hydraulic fracturing
                    Jnrrbt: Quarrying
                Jnrrf: Fuel processing
                    Jnrrfc: Coal processing
                        Jnrrfcg: Coal gasification
                        Jnrrfch: Coal hydrogenation
                        Jnrrfcm: Coal liquefaction
                        Jnrrfcp: Coking
                    Jnrrfh: Hydrogen production
                    Jnrrfp: Petroleum refining
                    Jnrrfv: Fuel storage
                        Jnrrfvh: Hydrogen storage
                Jnrrh: Beneficiation
                Jnrrk: Land reclamation
                    Jnrrkr: Revegetation
                    Jnrrkt: Reforestation
                Jnrrm: Natural gas distribution systems
                Jnrrp: Electric power generation and transmission
                    Jnrrpe: Electric power supply
                    Jnrrpp: Electric power generation
                        Jnrrpph: Hydroelectric power generation
                        Jnrrppn: Nuclear power generation
                            Jnrrppnn: Reactor fuel cycle
                        Jnrrpps: Solar power generation
                        Jnrrppt: Thermal power generation
                        Jnrrppu: Waste heat utilization
                        Jnrrppw: Wind power generation
                    Jnrrpt: Electric power transmission
                        Jnrrpte: Electric power conditioning
                        Jnrrptj: Interconnection (Electric power)
                    Jnrrpv: Energy storage systems
                Jnrrw: Water resources development
                    Jnrrwd: Desalination
                    Jnrrwp: Ocean development
            Jnru: Resource utilization
                Jnrue: Energy consumption
                    Jnruef: Fuel consumption
                Jnruw: Water consumption
K: Economic and social factors
    Ka: Economic factors
        Kab: Factors of production
            Kabe: Land
                Kabeu: Land use
                    Kabeum: Land use models
                Kabev: Land values
                Kabex: Greenways
                Kabey: Zoning
                    Kabeyo: Open space control
            Kabk: Labor
                Kabkb: Labor force
                Kabkm: Labor market
                Kabkn: Jobs
                    Kabknj: Job opportunities
                    Kabknp: Occupations
                    Kabknt: Transportation careers
                Kabkp: Employment
                    Kabkpp: Professional employment
                    Kabkpu: Unemployment
                Kabkr: Labor relations
                    Kabkrn: Labor negotiations
                        Kabkrnp: Collective bargaining
                        Kabkrns: Strikes
                            Kabkrnsa: Arbitration
                            Kabkrnsm: Mediation
                    Kabkrp: Labor agreements
            Kabq: Capital
                Kabqi: Infrastructure
                    Kabqip: Property
                        Kabqipe: Real property
                        Kabqipj: Indian reservations
                        Kabqipr: Private property
                        Kabqipu: Public land
                        Kabqipw: Public works
                Kabqm: Money
                    Kabqmc: Currency
                        Kabqmcd: Devaluation (Currency)
        Kad: Economic conditions
            Kadb: Consumer behavior
                Kadbp: Consumer preferences
                    Kadbpr: Revealed preferences
                    Kadbpu: Stated preferences
                Kadbs: Customer satisfaction
            Kadm: Markets
                Kadmd: Supply
                Kadme: Demand
                Kadmq: Equilibrium (Economics)
                Kadmx: Prices
                Kadmy: Rationing
            Kadr: Consumption
                Kadrr: Consumption rates
            Kadt: Savings
            Kadu: Shortages
            Kady: Business cycles
                Kadyi: Inflation
                Kadyr: Recession
                Kadyt: Depression (Business cycle)
        Kai: Economic indicators
            Kaib: Gross domestic product
            Kaig: Gross national product
            Kaip: Balance of payments
            Kait: Foreign exchange
            Kaix: Index numbers
    Kc: Economic analysis
        Kcb: Economic development
        Kcd: Economic efficiency
        Kcf: Economic forecasting
        Kcg: Economic growth
        Kcm: Economies of scale
        Kcs: Consumers surplus
        Kct: Producers surplus
        Kcu: Elasticity (Economics)
    Kd: Economic models
        Kdi: Input output models
        Kdu: Utility theory
        Kdx: Location theory
    Kf: Economic policy
    Kh: Social factors
        Kha: Social change
        Khb: Population
            Khbd: Population density
            Khbf: Population forecasting
            Khbg: Population growth
            Khbm: Population movements
                Khbmm: Mobility
                Khbmn: Migration
            Khbu: Urban population
            Khby: Census
        Khd: Life expectancy
        Khe: Life span
        Khj: Living conditions
            Khjm: Standard of living
            Khjp: Life styles
            Khjq: Quality of life
            Khjs: Value of life
            Khju: Value of time
        Khm: Institutional issues
        Khq: Demographics
        Khr: Culture (Social sciences)
            Khrr: Cultural resources
            Khrv: Social values
        Khs: Social class
        Kht: Special events
            Khte: Exhibitions
            Khtp: Olympic games
    Kj: Socioeconomic factors
        Kjf: Housing
    Kk: Impacts
        Kke: Economic impacts
        Kkf: Social impacts
        Kkt: Benefits
            Kkte: Economic benefits
            Kktf: Social benefits
                Kktfb: Affirmative action
            Kktn: Nonuser benefits
                Kktnc: Value capture
            Kktu: User benefits
        Kku: Externalities
    Ku: Social service
    Kw: Public participation
        Kwc: Community action programs
        Kwh: Adopt-a-highway programs
        Kwp: Public opinion
    Kx: Socioeconomic development
        Kxq: Regional development
            Kxqa: Regional analysis
        Kxr: Rural development
        Kxu: Urban development
            Kxug: Urban growth
            Kxus: Urban sprawl
            Kxuv: Urbanization
M: Persons and personal characteristics
    Mb: Age groups
        Mbb: Infants
        Mbc: Children
            Mbcc: Preschool children
        Mbe: School children
        Mbf: Adolescents
        Mbp: Adults
            Mbpc: Young adults
            Mbpe: Aged
    Md: Gender
        Mdf: Females
            Mdfp: Pregnant women
        Mdm: Males
    Me: Persons by educational level
        Mes: Students
            Mesa: Elementary school students
            Mesb: High school students
            Mesc: College students
            Mesg: Graduate students
            Mesx: School dropouts
        Met: Graduates
            Meta: High school graduates
            Metb: College graduates
        Mew: Illiterates
    Mf: Families
        Mfm: Marital status
        Mfp: Parents
    Mg: Households
    Mh: Persons by race and ethnicity
        Mha: Ethnic groups
        Mhb: Race
        Mhc: Blacks
            Mhcb: African Americans
        Mhd: Asians
        Mhe: Whites
        Mhf: Inuit
        Mhh: Hispanics
        Mhm: Native Americans
        Mhv: Indigenous peoples
        Mhx: Minorities
    Mj: Persons by language backgrounds
    Mk: Persons by socioeconomic levels
        Mkb: Upper income groups
        Mkc: Middle income groups
        Mkd: Low income groups
            Mkdw: Welfare recipients
        Mke: Persons by employment status
            Mkee: Employed
            Mkeu: Unemployed
            Mkew: Working class
        Mkh: Persons by housing characteristics
            Mkhb: Landowners
            Mkhd: Tenants
            Mkhe: Transients
            Mkhf: Squatters
            Mkhh: Homeless persons
            Mkhk: Landlords
            Mkhr: Residents
    Ml: Crowds
    Mm: Physically handicapped persons
        Mmb: Visually impaired persons
            Mmbd: Blind persons
            Mmbk: Color blind persons
        Mmd: Hearing impaired persons
            Mmda: Deaf persons
        Mmg: Amputees
        Mmk: Diabetics
    Mp: Mentally handicapped persons
        Mpr: Mentally retarded persons
    Ms: Personnel
        Msa: Administrative and managerial personnel
            Msaa: Administrative personnel
            Msab: Managerial personnel
                Msabt: Traffic managers
            Msae: Executives
            Msaf: Entrepreneurs
            Msas: Supervisors
            Msau: Employers
        Msb: Employees
            Msbb: Part time employees
            Msbg: Government employees
            Msbk: Laborers
            Msbp: Operators (Persons)
        Msc: Cargo handling personnel
            Mscb: Longshoremen
            Mscj: Lumpers
        Msd: Communications and control personnel
            Msdc: Air traffic controllers
            Msdd: Dispatchers
            Msdr: Radar operators
        Mse: Construction and maintenance personnel
            Msec: Ground crews
            Msei: Inspectors
            Msek: Maintenance personnel
                Msekr: Road crews
                    Msekra: Road construction workers
                    Msekrf: Flaggers
            Msem: Mechanics (Persons)
            Mses: Shipyard personnel
            Msew: Divers
        Msf: Education and training personnel
            Msfb: Teachers
            Msfd: Instructors
                Msfdd: Driving instructors
            Msfe: Driver examiners
        Msg: Engineering personnel
            Msgb: Engineers
                Msgbb: Civil engineers
                    Msgbbe: Transportation engineers
                    Msgbbh: Highway engineers
                    Msgbbr: Railroad engineers
                    Msgbbt: Traffic engineers
                Msgbm: Mechanical engineers
                    Msgbma: Automobile engineers
        Msk: Firefighters
        Msm: Medical personnel
            Msmd: Physicians
            Msmp: Allied health personnel
                Msmpa: Ambulance personnel
                Msmpm: Medical technicians
                    Msmpme: Emergency medical technicians
                Msmpp: Paramedics
            Msmw: Patients
        Msn: Military personnel
            Msnf: Air Force personnel
            Msng: Army personnel
            Msnn: Navy personnel
        Msp: Professional personnel
        Msq: Novices
        Mss: Scientific personnel
            Mssr: Researchers
            Msss: Scientists
            Msst: Technicians
        Mst: Specialists
        Msv: Volunteers
        Msw: Offenders and victims
            Mswa: Offenders
                Mswab: Repeat offenders
                Mswac: Recidivists
            Mswr: Trespassers
            Mswt: Traffic violators
            Mswv: Victims
                Mswva: Accident victims
                    Mswvab: Aircraft accident victims
                    Mswvat: Traffic accident victims
                Mswvc: Crime victims
        Msx: Law enforcement and criminal justice personnel
            Msxj: Judges
            Msxt: Attorneys
            Msxu: Law enforcement personnel
                Msxum: Police
                Msxus: Sky marshals
            Msxv: Interrogators
            Msxw: Witnesses
        Msy: Groups
            Msya: Advisory groups
            Msyb: Advocacy groups
            Msyf: Focus groups
            Msyj: Interest groups
            Msyk: Committees
            Msyl: Teams
                Msyld: Design teams
                Msylm: Multidisciplinary teams
            Msym: Market segmented groups
                Msymc: Consumers
                Msymd: Customers
                Msymj: Clients
                Msyms: Shoppers
            Msyp: Peer groups
            Msys: Special user groups
            Msyt: Coalitions
            Msyv: Stakeholders
            Msyx: Group dynamics
    Mt: Vehicle personnel
        Mtb: Flight personnel
            Mtbb: Air pilots
                Mtbbd: Airline pilots
                Mtbbg: General aviation pilots
                    Mtbbgb: Business aviation pilots
                    Mtbbgh: Helicopter pilots
            Mtbd: Air navigators
            Mtbf: Flight crews
            Mtbg: Flight attendants
        Mtg: Ground vehicle operators
            Mtgh: Highway vehicle operators
                Mtghd: Drivers
                    Mtghdb: Automobile drivers
                    Mtghdc: Commercial drivers
                        Mtghdcb: Bus drivers
                            Mtghdcbe: Extraboards
                            Mtghdcbs: School bus drivers
                        Mtghdcc: Chauffeurs
                        Mtghdcp: Professional drivers
                        Mtghdcr: Taxicab drivers
                        Mtghdct: Truck drivers
                        Mtghdcu: Test drivers
                    Mtghdd: Ambulance drivers
                    Mtghdf: Driver categories
                        Mtghdfa: Recently qualified drivers
                        Mtghdfb: Low risk drivers
                            Mtghdfba: Defensive drivers
                        Mtghdfc: High risk drivers
                            Mtghdfca: Accident prone drivers
                            Mtghdfcp: Problem drivers
                            Mtghdfcs: Reckless drivers
                            Mtghdfct: Impaired drivers
                                Mtghdfctd: Drunk drivers
                                Mtghdfctr: Drugged drivers
                            Mtghdfcu: Aged drivers
                            Mtghdfcw: Teenage drivers
                            Mtghdfcx: Handicapped drivers
                            Mtghdfcy: Designated drivers
                    Mtghdr: Driver records
                Mtghm: Motorcyclists
                Mtghs: Moped drivers
                Mtghv: Cyclists
            Mtgr: Train crews
                Mtgra: Locomotive engineers
                Mtgrb: Brakemen
                Mtgrf: Firemen (Locomotives)
                Mtgrh: Conductors (Trains)
                Mtgrt: Trainmen
        Mtj: Shipboard personnel
            Mtjc: Ship crews
            Mtjd: Ship officers
            Mtjg: Ship pilots
            Mtjh: Ship navigators
            Mtjm: Marine engineers
            Mtjs: Merchant seamen
        Mtu: Transit personnel
            Mtua: Transit operators
    Mw: Travelers
        Mwa: Passengers
            Mwat: Transit riders
                Mwatc: Captive riders
                Mwate: Transportation disadvantaged persons
            Mwau: School bus passengers
            Mwax: Stowaways
        Mwc: Commuters
        Mwg: Vehicle occupants
            Mwgf: Front seat occupants
            Mwgr: Rear seat occupants
        Mwu: Tourists
        Mwx: Pedestrians
    Mx: Human characteristics
        Mxa: Human factors
            Mxah: Human error
        Mxb: Physical condition
            Mxba: Physical fitness
            Mxbb: Physiological aspects
            Mxbc: Health
                Mxbcb: Breath
                Mxbcc: Blood pressure
                Mxbcd: Heart rate
                Mxbcm: Metabolism
            Mxbd: Bodily fluids
                Mxbdb: Blood
                Mxbds: Saliva
                Mxbdu: Urine
            Mxbe: Comfort
            Mxbf: Fatigue (Physiological condition)
                Mxbfd: Drowsiness
            Mxbg: Circadian rhythms
                Mxbgj: Jet lag
            Mxbh: Anthropometry
                Mxbhm: Human body mass
                Mxbhs: Human body size
            Mxbp: Posture
            Mxbr: Sleep
                Mxbrd: Sleep disorders
            Mxbs: Stress (Physiology)
            Mxbt: Tolerance (Physiology)
            Mxbv: Vision
                Mxbvc: Color vision
                Mxbvf: Field of vision
                Mxbvh: Dark adaptation
                Mxbvn: Night vision
                Mxbvp: Peripheral vision
                Mxbvq: Eye location
                Mxbvr: Eye fixations
                Mxbvs: Eye movements
                Mxbvt: Vision tests
            Mxbw: Speech
                Mxbwl: Language
                    Mxbwlb: Bilingualism
            Mxbx: Age
        Mxc: Physical handicaps
            Mxcr: Vision disorders
                Mxcrb: Blindness
                Mxcrc: Color blindness
            Mxct: Hearing loss
                Mxctd: Deafness
        Mxk: Mental condition
            Mxkc: Conflict (Psychology)
            Mxkp: Psychological aspects
                Mxkpt: Psychological tests
            Mxks: Stress (Psychology)
            Mxkt: Tolerance (Psychology)
            Mxku: Adaptation (Psychology)
        Mxm: Mental disorders
            Mxmb: Cognitive impairment
                Mxmbb: Attention deficit hyperactivity disorder
                Mxmbd: Dementia
                    Mxmbdb: Alzheimer's disease
            Mxmc: Depression (Mental condition)
            Mxmd: Dissociation
            Mxmu: Mental illness
            Mxmw: Posttraumatic stress disorder
        Mxn: Mental retardation
        Mxp: Personality
            Mxpb: Behavior
                Mxpbr: Risk taking
            Mxpd: Attitudes
                Mxpda: Acceptance
                Mxpdd: Adjustment (Psychology)
                Mxpdt: Trust (Psychology)
        Mxq: Emotions
            Mxqa: Aggression
                Mxqar: Road rage
            Mxqb: Annoyance
            Mxqc: Anger
            Mxqd: Distress
            Mxqf: Fear
                Mxqff: Fear of flying
            Mxqx: Anxiety
        Mxr: Abilities
            Mxra: Ability tests
            Mxrb: Aptitude
                Mxrbt: Aptitude tests
            Mxrc: Alertness
                Mxrcg: Attention
                Mxrcm: Attention lapses
                Mxrcv: Vigilance
            Mxrd: Cognition
                Mxrdb: Awareness
                Mxrdc: Comprehension
                Mxrdh: Human information processing
                Mxrdk: Knowledge
                Mxrdu: Understanding
                    Mxrdul: Reading
                        Mxrdulm: Map reading
            Mxrg: Learning
            Mxri: Intelligence
                Mxria: Intelligence quotient
            Mxrj: Judgment (Human characteristics)
            Mxrm: Motor skills
            Mxrr: Motor reactions
                Mxrra: Reaction time
            Mxrs: Memory
                Mxrsd: Memory devices
        Mxs: Motivation
        Mxt: Perception
            Mxta: Auditory perception
            Mxtb: Olfactory perception
            Mxtd: Depth perception
            Mxtm: Motion perception
            Mxts: Distance perception
            Mxtu: Velocity perception
            Mxtv: Visual perception
            Mxtw: Wayfinding
            Mxtx: Tactile perception
        Mxw: Distraction
        Mxy: Human subject testing
            Mxyc: Controlled trials
    My: Anatomy
        Myb: Skin and hair system
            Mybd: Skin
        Myc: Nervous system
            Myce: Brain
            Mycn: Nerves
            Mycs: Spinal cord
        Myd: Head
            Myda: Head motion range
            Mydb: Face
                Mydbe: Eye
                Mydbh: Ear
                Mydbn: Nose
            Mydd: Skull
        Mye: Neck
            Myea: Neck motion range
        Myf: Shoulder
        Myh: Thorax
            Myhh: Heart
            Myhm: Lungs
            Myhr: Ribs
        Myi: Back
        Myj: Spinal column
            Myjg: Vertebrae
        Myk: Abdomen
            Mykb: Stomach
            Mykm: Liver
            Mykv: Viscera
        Myn: Pelvis
        Myp: Extremities
            Mypb: Upper extremities
                Mypbh: Arm
                    Mypbha: Hand
            Mypd: Lower extremities
                Mypde: Hip
                Mypdg: Leg
                    Mypdgf: Femur
                    Mypdgk: Knee
                    Mypdgq: Ankle
                    Mypdgr: Foot
                        Mypdgrt: Toes
        Mys: Skeletal system
            Mysb: Bones
            Mysj: Joints (Anatomy)
        Myt: Muscular system
            Mytm: Muscles
            Mytt: Tendons
            Myty: Muscular forces
        Myu: Musculoskeletal system
        Myv: Cardiovascular system
            Myva: Arteries
            Myvg: Veins
            Myvk: Capillaries
            Myvr: Respiratory system
        Myx: Anatomical models
N: Organizations
    Nb: Businesses
        Nbb: Carriers
            Nbba: Carriers by type of service
                Nbbaf: For hire carriers
                    Nbbafc: Common carriers
                    Nbbafd: Contract carriers
                    Nbbafe: Exempt carriers
                Nbbah: Full service carriers
                Nbbam: Low cost carriers
                Nbbap: Private carriers
            Nbbc: Carriers by mode
                Nbbcb: Airlines
                    Nbbcbb: Local service airlines
                    Nbbcbc: Commuter airlines
                    Nbbcbd: Regional airlines
                    Nbbcbf: Supplemental airlines
                    Nbbcbh: Helicopter lines
                Nbbcd: Motor carriers
                    Nbbcdb: Bus lines
                        Nbbcdbj: Intercity bus lines
                    Nbbcdt: Truck lines
                        Nbbcdtm: Moving industry
                        Nbbcdtp: Owner operators
                Nbbcg: Railroads
                    Nbbcga: Short line railroads
                    Nbbcgf: Regional railroads
                    Nbbcgp: Cable railroads
                    Nbbcgq: Electric railroads
                    Nbbcgr: Street railroads
                    Nbbcgt: Switching and terminal companies
                    Nbbcgv: Industrial railroads
                    Nbbcgy: Private car lines
                Nbbck: Pipeline companies
                Nbbcm: Ship lines
                    Nbbcma: Cruise lines
                    Nbbcmb: Barge lines
                Nbbct: Taxicab companies
                Nbbcu: Transit operating agencies
        Nbc: Freight transportation support businesses
            Nbcc: Freight forwarders
                Nbcca: Air freight forwarders
                Nbccd: Ocean freight forwarders
            Nbcd: Freight consolidators
            Nbce: Freight brokers
            Nbcs: Ship agencies
            Nbct: Ship brokers
        Nbd: Passenger transportation support businesses
            Nbdd: Travel agents
            Nbde: Tour operators
        Nbe: Distribution support businesses
            Nbef: Freight service bureaus
            Nbet: Third party logistics providers
            Nbew: Warehousing and storage businesses
        Nbf: Package and mail businesses
        Nbh: Motor vehicle dealers
            Nbhd: Automobile dealers
            Nbht: Truck dealers
        Nbk: Equipment leasing and rental businesses
        Nbm: Repair and maintenance businesses
            Nbmv: Automobile repair shops
        Nbq: Parking industry
        Nbr: Financial, insurance and real estate businesses
            Nbrb: Banking industry
            Nbrh: Insurance industry
            Nbrp: Real estate industry
        Nbs: Suppliers
        Nbt: Lodging businesses
        Nbu: Public utilities
            Nbue: Electric utilities
            Nbug: Gas utilities
            Nbuw: Water utilities
        Nbv: Computer online services
            Nbvj: Internet service providers
        Nby: General service businesses
            Nbya: Contractors
                Nbyaa: Subcontractors
            Nbyd: Consultants
            Nbyf: Developers
            Nbyg: Designers
            Nbyk: Engineering services
    Nc: Industries
        Nce: Transportation equipment industry
            Ncec: Container equipment industry
            Ncef: Aerospace industry
                Ncefa: Aircraft industry
                    Ncefau: Used aircraft industry
            Nceg: Aviation
                Ncegc: Civil aviation
                Ncegg: General aviation
                    Ncegga: Agricultural aviation
                    Nceggb: Business aviation
                Ncegm: Military aviation
                    Ncegmd: Air drop
                    Ncegmf: Military airlift
            Nceh: Road construction industry
            Ncem: Motor vehicle industry
                Ncema: Automobile industry
                Ncemb: Automobile parts industry
                    Ncembt: Tire industry
                Ncemu: Used vehicle industry
            Ncer: Railroad equipment industry
                Ncerc: Carbuilders
                Ncerd: Locomotive builders
            Nces: Maritime industry
                Ncesm: Military sealift
        Ncg: Nontransportation industries
            Ncgc: Chemical industry
            Ncgd: High technology industries
            Ncge: Electronics industry
            Ncgf: Food industry
            Ncgg: Glass industry
            Ncgh: Machinery manufacturing industry
            Ncgi: Metal industry
                Ncgii: Iron and steel industry
            Ncgj: Textile industry
            Ncgk: Construction industry
                Ncgkc: Cement industry
                Ncgkf: Concrete industry
            Ncgm: Mining and extractive industries
                Ncgmc: Coal industry
                Ncgmg: Gas industry
                Ncgmp: Petroleum industry
            Ncgr: Agricultural industry
                Ncgrf: Farming
                    Ncgrff: Farms
            Ncgs: Fisheries
                Ncgsf: Fishing
            Ncgt: Forest products industry
                Ncgtg: Lumber industry
                Ncgtp: Paper industry
    Nd: Service agencies
        Nde: Educational services
            Ndes: Schools
            Ndeu: Universities and colleges
        Ndh: Health care services
        Nds: Social service agencies
            Ndsd: Day care centers
    Ng: Governments
        Ngd: Levels of government
            Ngdc: Federal government
            Ngdf: State government
            Ngdh: Local government
                Ngdhc: County government
                Ngdhm: Metropolitan government
                Ngdhs: City government
            Ngdr: Regional government
            Ngdt: Tribal government
        Ngg: Government agencies
            Ngga: Federal government agencies
            Nggb: State government agencies
                Nggbd: State departments of transportation
                Nggbh: State highway departments
                Nggbm: State motor vehicle departments
            Nggj: Transportation departments
            Nggk: Local government agencies
                Nggka: Public works departments
                Nggkd: Highway departments
                Nggkf: Fire departments
                Nggkp: Police departments
                Nggks: Metropolitan planning organizations
                Nggkt: Councils of government
            Nggm: Districts and authorities
                Nggme: Enterprise districts
                Nggmg: Port districts
                Nggmh: Port authorities
                Nggmt: Transit authorities
                    Nggmtb: Transit boards
        Ngr: Intergovernmental relations
            Ngrg: Interstate compacts
            Ngrh: International compacts
        Ngt: Interagency relations
        Ngv: Public service
    Nm: Military organizations
    Ns: Membership organizations
        Nsa: Associations
            Nsas: Shippers associations
                Nsasr: Rate bureaus
                Nsass: Shipping conferences
        Nse: Societies
            Nsee: Engineering societies
        Nsh: Highway safety organizations
        Nsj: Labor unions
        Nst: Trade associations
        Nsw: Transportation management associations
    Nt: Forms of business or industry
        Ntc: Corporations
            Ntca: Nonprofit corporations
            Ntci: Multinational corporations
        Nte: Conglomerates
        Ntg: Cooperatives
        Nth: Small business
        Ntj: Monopoly
        Ntk: Disadvantaged business enterprises
        Ntm: Minority business enterprises
        Ntn: Women owned business enterprises
        Ntp: Private enterprise
        Ntr: Partnerships
            Ntrd: Public private partnerships
            Ntrg: Intergovernmental partnerships
            Ntrs: Strategic alliances
    Nv: Globalization
    Ny: Organized crime
P: Facilities
    Pb: Structures
        Pbc: Structures by building system
            Pbca: Cast in place structures
            Pbcb: Composite structures
            Pbcc: Concrete structures
            Pbcd: Continuous structures
            Pbce: Earthquake resistant structures
            Pbcf: Elevated structures
            Pbcg: Flexible structures
            Pbch: Framed structures
            Pbci: Gravity structures
            Pbcj: Hinged structures
            Pbck: Honeycomb structures
                Pbckl: Cellular structures
            Pbcm: Inflatable structures
            Pbcn: Modular structures
            Pbcp: Multistory structures
            Pbcq: Prefabricated structures
            Pbcr: Rigid structures
            Pbcs: Steel structures
            Pbct: Skewed structures
            Pbcu: Suspended structures
                Pbcud: Aerial tramways
            Pbcv: Tubular structures
            Pbcw: Web stiffened structures
            Pbcx: Weldments
            Pbcy: Wood structures
            Pbcz: Smart structures
        Pbp: Structural parts
            Pbpb: Structural members
                Pbpba: Arches
                Pbpbb: Ceilings
                Pbpbc: Chimneys
                Pbpbd: Conduits
                    Pbpbdc: Ducts
                        Pbpbdcb: Acoustic ducts
                        Pbpbdce: Diffusers
                    Pbpbdo: Open channels
                Pbpbe: Floors
                Pbpbf: Foundations
                    Pbpbfb: Abutments
                    Pbpbfd: Anchor walls
                    Pbpbff: Anchorages
                    Pbpbfh: Bedding
                    Pbpbfj: Floating foundations
                    Pbpbfk: Footings
                        Pbpbfkj: Isolated footings
                        Pbpbfkm: Mats (Footings)
                        Pbpbfks: Spread footings
                        Pbpbfku: Strip footings
                    Pbpbfm: Mat foundations
                    Pbpbfp: Mattresses (Foundations)
                    Pbpbfq: Piers (Supports)
                    Pbpbfs: Pile foundations
                    Pbpbfx: Strip foundations
                Pbpbg: Frames
                    Pbpbgd: Statically determinate frames
                    Pbpbgj: Statically indeterminate frames
                Pbpbh: Joints (Engineering)
                    Pbpbhb: Backing strips
                    Pbpbhc: Ball and socket joints
                    Pbpbhd: Butt joints
                    Pbpbhe: Construction joints
                    Pbpbhh: Contraction joints
                    Pbpbhk: Expansion joints
                    Pbpbhp: Lap joints
                    Pbpbhs: Longitudinal joints
                    Pbpbht: Sawed joints
                    Pbpbhu: Seams
                    Pbpbhv: Transverse joints
                Pbpbj: Lattices
                Pbpbk: Openings
                    Pbpbkb: Building entrances
                    Pbpbkc: Building exits
                        Pbpbkce: Emergency exits
                    Pbpbkd: Doors
                        Pbpbkdc: Casings
                    Pbpbkg: Grilles
                    Pbpbkv: Vents
                    Pbpbkw: Windows (Buildings)
                Pbpbl: Ramps, corridors and stairs
                    Pbpblc: Corridors
                    Pbpblr: Ramps
                    Pbpbls: Stairs
                        Pbpblsh: Half spaces (Building)
                Pbpbm: Rooms
                    Pbpbmb: Basements
                    Pbpbmc: Control rooms
                    Pbpbme: Engine rooms
                    Pbpbmh: Hospital emergency rooms
                Pbpbp: Roofs
                    Pbpbpd: Domes
                Pbpbt: Shells (Structural forms)
                Pbpbu: Slabs
                    Pbpbus: Slab on grade
                Pbpbv: Structural supports
                    Pbpbva: Bents
                    Pbpbvb: Brackets
                    Pbpbvc: Breakaway supports
                    Pbpbvd: Buttresses
                    Pbpbve: Concrete forms
                        Pbpbves: Sliding forms
                    Pbpbvf: Falsework
                        Pbpbvfs: Scaffolds
                    Pbpbvg: Lateral supports
                    Pbpbvh: Horizontal supports
                        Pbpbvhb: Braces
                        Pbpbvhj: Stringers
                        Pbpbvhu: Struts
                    Pbpbvr: Tie rods
                    Pbpbvt: Timbering
                    Pbpbvv: Vertical supports
                        Pbpbvvb: Beams
                            Pbpbvvbb: Box beams
                            Pbpbvvbc: Curved beams
                            Pbpbvvbj: I beams
                            Pbpbvvbm: Leaf springs
                            Pbpbvvbt: T beams
                            Pbpbvvbw: Thrie beams
                            Pbpbvvby: Tiebacks
                        Pbpbvvc: Cantilevers
                        Pbpbvvd: Columns
                        Pbpbvvg: Girders
                            Pbpbvvgb: Box girders
                            Pbpbvvgp: Plate girders
                        Pbpbvvj: Lagging (Earthwork)
                        Pbpbvvm: Piles (Supports)
                            Pbpbvvmb: Anchor piles
                            Pbpbvvmd: Batter piles
                            Pbpbvvmg: Bearing piles
                                Pbpbvvmge: End bearing piles
                                Pbpbvvmgf: Friction piles
                            Pbpbvvms: Sheet piling
                            Pbpbvvmv: Pile groups
                            Pbpbvvmw: Pile caps
                        Pbpbvvp: Poles (Supports)
                        Pbpbvvq: Posts
                        Pbpbvvr: Sign supports
                        Pbpbvvs: Studs
                            Pbpbvvss: Scantlings
                        Pbpbvvt: Trusses
                Pbpbw: Walls
                    Pbpbwc: Cutoff walls
                        Pbpbwcg: Grout curtains
                    Pbpbwd: Diaphragm walls
                    Pbpbwp: Parapets
                    Pbpbws: Shear walls
                    Pbpbwt: Thin walls
                Pbpbx: Welds
                    Pbpbxb: Butt welds
                    Pbpbxf: Fillet welds
                Pbpby: Structural members by elevation
                    Pbpbyb: Substructures
                    Pbpbyp: Superstructures
            Pbpv: Environmental and sanitary systems in buildings
                Pbpvb: Air conditioning systems
                Pbpvc: Cooling systems
                    Pbpvcr: Refrigeration systems
                Pbpve: Electrical systems
                    Pbpvew: Electrical wiring
                Pbpvh: Heating systems
                    Pbpvhe: Electric heating
                Pbpvj: Insulation systems
                Pbpvm: Lighting systems
                Pbpvp: Plumbing systems
                    Pbpvpt: Toilet facilities
                Pbpvv: Ventilation systems
            Pbpy: Transportation systems in buildings
                Pbpym: Elevators
                Pbpys: Escalators
    Pd: Specialized facilities
        Pdc: Construction sites
            Pdcw: Work zones
        Pdv: Underground structures
            Pdvp: Underground parking garages
            Pdvt: Tunnels
                Pdvtb: Parts of tunnels
                    Pdvtbm: Tunnel lining
                    Pdvtbr: Tunnel shafts
                        Pdvtbrc: Crossheadings
                    Pdvtbs: Tunnel supports
                        Pdvtbss: Shields (Tunnels)
                Pdvtr: Tunnels by use
                    Pdvtrn: Pedestrian tunnels
                    Pdvtrp: Pressure tunnels
                    Pdvtrr: Railroad tunnels
                        Pdvtrrs: Subways
                    Pdvtrv: Vehicular tunnels
                        Pdvtrvt: Toll tunnels
            Pdvw: Wells
        Pdw: Excavations, mines and oil fields
            Pdwe: Excavations
                Pdwep: Pits
                Pdweq: Quarries
                    Pdweqg: Gravel pits
                Pdwet: Trenches
                    Pdwetb: Trench backfill
                    Pdwetw: Slurry trenches
            Pdwm: Mines
                Pdwmc: Coal mines
            Pdwp: Oil fields
                Pdwpk: Observation wells
                Pdwpp: Oil pools
                Pdwpw: Oil wells
        Pdx: Embankments and retaining walls
            Pdxe: Embankments
            Pdxr: Retaining walls
                Pdxrc: Crib walls
                Pdxre: Earth walls
                Pdxrr: Reinforced concrete retaining walls
                Pdxrs: Sheet pile walls
            Pdxt: Components of embankments and retaining walls
                Pdxte: Embankment foundations
                Pdxtf: Fills
                    Pdxtff: Flowable fill
                    Pdxtfh: Hydraulic fills
                    Pdxtfr: Rockfills
                Pdxtr: Relieving platforms
        Pdy: Bridges and culverts
            Pdyb: Bridges
                Pdybb: Bridge members
                    Pdybbc: Bridge approaches
                    Pdybbf: Bridge substructures
                        Pdybbfb: Bridge abutments
                        Pdybbfc: Bridge anchorages
                        Pdybbfe: Bridge bearings
                            Pdybbfep: Bridge bearing pads
                        Pdybbff: Bridge foundations
                        Pdybbfp: Bridge piers
                        Pdybbfw: Bridge waterways
                    Pdybbs: Bridge superstructures
                        Pdybbsc: Bridge cables
                        Pdybbsf: Bridge decks
                        Pdybbsr: Bridge railings
                        Pdybbss: Bridge towers
                Pdybm: Types of bridges
                    Pdybmd: Types of bridges by design
                        Pdybmdb: Arch bridges
                        Pdybmdc: Cantilever bridges
                            Pdybmdcc: Cable stayed bridges
                        Pdybmdd: Covered bridges
                        Pdybmde: Curved bridges
                        Pdybmdg: Girder bridges
                            Pdybmdgb: Box girder bridges
                            Pdybmdgc: Continuous girder bridges
                            Pdybmdgp: Plate girder bridges
                        Pdybmdh: Long span bridges
                        Pdybmdi: Jointless bridges
                        Pdybmdj: Movable bridges
                            Pdybmdjb: Bascule bridges
                            Pdybmdjd: Drawbridges
                            Pdybmdjm: Lift bridges
                            Pdybmdjs: Swing bridges
                        Pdybmdm: Narrow bridges
                        Pdybmdn: Pontoon bridges
                        Pdybmdp: Prefabricated bridges
                            Pdybmdpb: Bailey bridges
                        Pdybmdr: Skew bridges
                        Pdybmds: Suspension bridges
                        Pdybmdt: Trestles
                        Pdybmdv: Truss bridges
                        Pdybmdx: Viaducts
                    Pdybmm: Types of bridges by material
                        Pdybmmc: Concrete bridges
                            Pdybmmcp: Prestressed concrete bridges
                            Pdybmmcr: Reinforced concrete bridges
                        Pdybmmm: Metal bridges
                        Pdybmmp: Masonry bridges
                        Pdybmmw: Wooden bridges
                    Pdybmu: Types of bridges by use
                        Pdybmuf: Historic bridges
                        Pdybmuh: Highway bridges
                            Pdybmuhc: Causeways
                            Pdybmuht: Toll bridges
                        Pdybmum: Military bridges
                        Pdybmup: Footbridges
                        Pdybmur: Railroad bridges
                            Pdybmurt: Elevated guideways
            Pdyr: Culverts
                Pdyrd: Types of culverts
                    Pdyrdb: Box culverts
                    Pdyrdc: Concrete culverts
                        Pdyrdcc: Concrete arch culverts
                        Pdyrdcr: Reinforced concrete culverts
                    Pdyrdm: Metal culverts
                        Pdyrdmb: Aluminum culverts
                        Pdyrdmf: Corrugated metal culverts
                    Pdyrdp: Pipe culverts
                        Pdyrdpc: Corrugated pipe culverts
                Pdyru: Parts of culverts
                    Pdyruj: Culvert inlets
                    Pdyrup: Culvert outlets
            Pdyw: Wildlife crossings
    Pf: Facilities and structures by use
        Pfb: Activity centers
            Pfbk: Kiosks
        Pfc: Commercial buildings
            Pfcp: Office buildings
                Pfcpd: Data processing centers
            Pfcr: Restaurants
                Pfcrf: Fast food restaurants
                    Pfcrfd: Drive in restaurants
            Pfcs: Shopping facilities
                Pfcsb: Convenience stores
                Pfcsc: Shopping centers
                    Pfcsct: Transit malls
        Pfd: Control centers
            Pfde: Control centers by function
                Pfdec: Airport control towers
                Pfdeg: Command centers
                Pfdep: Radar stations
                Pfder: Traffic control centers
            Pfdp: Parts of control centers
                Pfdpc: Control rooms
        Pfe: Correctional facilities
            Pfej: Jails
            Pfep: Prisons
        Pff: Dwellings
            Pffb: Apartment buildings
            Pffm: Mobile homes
            Pffs: Single family dwellings
        Pfg: Health care facilities
            Pfgc: Diagnostic centers
            Pfgh: Hospitals
                Pfghh: Hospital emergency rooms
        Pfh: Hotels
            Pfhm: Motels
        Pfk: Industrial buildings
            Pfkf: Factories
                Pfkfm: Mills
            Pfkp: Industrial plants
                Pfkpb: Asphalt plants
                Pfkpd: Coal gasification plants
                Pfkpe: Coal liquefaction plants
                Pfkpf: Concrete plants
                Pfkph: LNG plants
                Pfkpm: Mixing plants
                Pfkpp: Petroleum refineries
                Pfkpr: Pilot plants
                Pfkps: Steel plants
        Pfl: Maintenance facilities
        Pfm: Military facilities
            Pfmc: Command centers
            Pfmn: Naval shore facilities
            Pfmr: Radar stations
        Pfo: Public buildings
            Pfot: Theaters
        Pfq: Recreational facilities
            Pfqb: Amusement parks
            Pfqc: Casinos
            Pfqn: Parks
                Pfqnn: National parks
            Pfqp: Playgrounds
            Pfqs: Sports facilities
                Pfqss: Stadiums
        Pfr: Research and educational facilities
            Pfrk: Libraries
            Pfrl: Museums
            Pfrm: Laboratories
                Pfrmt: Test facilities
                    Pfrmtt: Test chambers
                        Pfrmttb: Anechoic chambers
                    Pfrmty: Types of test facilities
                        Pfrmtym: Model basins
                        Pfrmtyp: Proving grounds
                        Pfrmtyt: Test sections
                        Pfrmtyu: Water tunnels (Test facilities)
                        Pfrmtyw: Wind tunnels
            Pfru: Universities and colleges
                Pfruc: Campuses
            Pfrw: High schools
        Pfs: Storage facilities
            Pfsg: Grain elevators
            Pfss: Silos
            Pfst: Storage tanks
            Pfsw: Warehouses
        Pft: Temporary structures
        Pfw: Waste disposal facilities
            Pfwj: Junkyards
            Pfwm: Landfills
                Pfwms: Sanitary landfills
            Pfwr: Radioactive waste facilities
        Pfx: Weather stations
        Pfy: Minor structures
            Pfyf: Fences
                Pfyfs: Snow fences
            Pfyg: Garages
            Pfyj: Gates
            Pfys: Shelters
                Pfysw: Windbreaks
            Pfyt: Towers
    Pm: Transportation, hydraulic and utility facilities
        Pme: Intermodal facilities
            Pmeb: Transportation buildings
            Pmec: Transportation corridors
            Pmet: Intermodal terminals
                Pmetf: Freight terminals
                    Pmetfc: Cargo facilities
                        Pmetfcm: Loading facilities
                        Pmetfcu: Unloading facilities
                Pmetp: Passenger terminals
            Pmeu: Transit centers
                Pmeut: Transfer centers
            Pmey: Intermodal yards
        Pmf: Air transportation facilities
            Pmfc: Airports
                Pmfcb: Types of airports
                    Pmfcbb: Air bases
                    Pmfcbg: General aviation airports
                    Pmfcbh: Heliports
                    Pmfcbj: International airports
                    Pmfcbp: Offshore airports
                    Pmfcbq: Private airports
                    Pmfcbs: STOL ports
                    Pmfcbu: Utility airports
                    Pmfcbv: V/STOL airports
                Pmfcg: Airport facilities
                    Pmfcgc: Airport terminals
                        Pmfcgcb: Aprons (Airports)
                        Pmfcgcc: Air cargo terminals
                        Pmfcgcd: Concourses (Airports)
                        Pmfcgcf: Departure lounges
                        Pmfcgcg: Aircraft gates
                        Pmfcgcj: Intra airport transportation facilities
                            Pmfcgcjc: Airbridges
                            Pmfcgcjm: Mobile lounges
                        Pmfcgcp: Airport parking facilities
                        Pmfcgcs: Satellite terminals (Airports)
                        Pmfcgct: Airport ticket counters
                    Pmfcgf: Hangars
                    Pmfcgm: Landing fields
                        Pmfcgmr: Airport runways
                            Pmfcgmrj: Intersecting runways
                            Pmfcgmrp: Parallel runways
                        Pmfcgmt: Taxiways
            Pmfg: Air traffic control facilities
                Pmfgc: Air route traffic control centers
                Pmfgf: Airport control towers
                Pmfgs: Flight service stations
            Pmfk: Airstrips
                Pmfke: Emergency airstrips
            Pmfl: Landing mats
            Pmfm: Airways
        Pmg: Communication facilities
            Pmgr: Radio stations
            Pmgt: Telecommuting centers
        Pmh: Hydraulic structures
            Pmhb: Harbors
                Pmhbc: Types of harbors
                    Pmhbcd: Deepwater harbors
                    Pmhbcm: Marinas
                Pmhbm: Components of harbors
                    Pmhbmp: Ports
                        Pmhbmpc: Types of ports
                            Pmhbmpcm: River ports
                            Pmhbmpcp: Seaports
                            Pmhbmpcs: Superports
                        Pmhbmpm: Port structures
                            Pmhbmpmb: Wharves
                                Pmhbmpmbd: Types of wharves
                                    Pmhbmpmbdf: Quays
                                    Pmhbmpmbdr: Piers (Wharves)
                                Pmhbmpmbr: Wharf components
                                    Pmhbmpmbrb: Aprons (Wharves)
                                    Pmhbmpmbrf: Berthing facilities
                                    Pmhbmpmbrg: Bollards
                                    Pmhbmpmbrj: Fenders (Wharves)
                                    Pmhbmpmbrm: Gantry cranes
                                    Pmhbmpmbrr: Dolphins (Piles)
                                    Pmhbmpmbrt: Waterfront structures
                                        Pmhbmpmbrtt: Transit sheds (Wharves)
                            Pmhbmpmf: Docks
                                Pmhbmpmfd: Drydocks
                                Pmhbmpmff: Floating docks
                            Pmhbmpmm: Moorings
                                Pmhbmpmmb: Mooring buoys
                                Pmhbmpmmd: Offshore moorings
                                Pmhbmpmmp: Single point moorings
                            Pmhbmpmt: Marine terminals
                                Pmhbmpmtb: Bulk cargo terminals
                                Pmhbmpmtd: Coal terminals
                                Pmhbmpmtf: Container terminals
                                Pmhbmpmtg: Ferry terminals
                                Pmhbmpmth: Grain terminals
                                Pmhbmpmtj: LASH terminals
                                Pmhbmpmtm: LNG terminals
                                Pmhbmpmtp: Offshore terminals
                                Pmhbmpmtq: Ore terminals
                                Pmhbmpmtr: Petroleum terminals
                                Pmhbmpmtv: VLCC ports
                    Pmhbmy: Shipyards
            Pmhd: Coast and river protective works
                Pmhdb: Berms
                Pmhdc: Breakwaters
                    Pmhdcf: Floating breakwaters
                    Pmhdcr: Rubble mound breakwaters
                Pmhdd: Bulkheads (Hydraulics)
                Pmhdh: Dikes
                    Pmhdhs: Spur dikes
                Pmhdj: Groins (Hydraulics)
                Pmhdk: Jetties
                Pmhdm: Levees
                Pmhdp: Polders
                Pmhdr: Revetments
                Pmhdt: Riprap
                Pmhdv: Sea walls
            Pmhe: Lighthouses
            Pmhj: Canals and waterways
                Pmhjc: Canals
                    Pmhjcj: Interoceanic canals
                Pmhjw: Waterways
                    Pmhjwj: Inland waterways
                    Pmhjwn: Intracoastal waterways
                Pmhjy: Parts of canals and waterways
                    Pmhjyb: Banks (Waterways)
                    Pmhjyd: Canal linings
                    Pmhjye: Channels (Waterways)
                        Pmhjyeb: Benching
                        Pmhjyem: Channel linings
                        Pmhjyes: Streambeds
                    Pmhjyh: Flumes
                    Pmhjyn: Locks (Waterways)
                        Pmhjync: Lock chambers
                        Pmhjyng: Lock gates
                        Pmhjynm: Lift gates (Locks)
                    Pmhjys: Stilling basins
                    Pmhjyu: Substrates (Waterways)
            Pmhm: Dams
                Pmhmb: Types of dams
                    Pmhmbb: Arch dams
                    Pmhmbc: Cofferdams
                    Pmhmbd: Concrete dams
                    Pmhmbe: Earth dams
                    Pmhmbg: Gravity dams
                    Pmhmbr: Rockfill dams
                    Pmhmbw: Weirs
                Pmhmr: Parts of dams
                    Pmhmrf: Dam foundations
                    Pmhmrh: Fish ladders
                    Pmhmrm: Sluices
                    Pmhmrp: Spillways
            Pmhp: Irrigation and drainage structures
                Pmhpd: Drainage structures
                    Pmhpdb: Catch basins
                    Pmhpdc: Detention basins
                    Pmhpdd: Ditches
                    Pmhpde: Drainage canals
                    Pmhpdf: Drains
                        Pmhpdfe: Edge drains
                        Pmhpdff: Filter drains
                        Pmhpdfh: Horizontal drains
                        Pmhpdfr: Sand drains
                        Pmhpdfs: Subdrains
                        Pmhpdfv: Vertical drains
                        Pmhpdfx: Wick drains
                    Pmhpdh: Drainage basins
                    Pmhpdj: Drainage blankets
                    Pmhpdm: Grates
                    Pmhpdp: Gutters
                    Pmhpdq: Manholes
                    Pmhpds: Sewers
                        Pmhpdss: Storm sewers
                    Pmhpdu: Sumps
                    Pmhpdv: Swales
                Pmhpj: Irrigation structures
                    Pmhpjj: Irrigation canals
                    Pmhpjm: Laterals (Irrigation)
            Pmhs: Water supply and distribution structures
                Pmhsf: Water supply structures
                    Pmhsfb: Aqueducts
                    Pmhsff: Desalination plants
                    Pmhsfr: Reservoirs
                    Pmhsft: Water pipelines
                        Pmhsftp: Piping systems
                    Pmhsfw: Water tunnels
                    Pmhsfy: Water wells
                Pmhsm: Water distribution structures
                    Pmhsmf: Water mains
                    Pmhsmn: Water towers
                    Pmhsmt: Waterworks
            Pmhv: Sewerage structures
                Pmhvs: Sewage holding tanks
                Pmhvt: Sewage treatment plants
                Pmhvu: Sanitary sewers
            Pmhy: Offshore structures
                Pmhyc: Caissons
                Pmhyf: Floating structures
                Pmhym: Moored structures
                Pmhyp: Offshore platforms
                    Pmhypd: Offshore drilling platforms
                Pmhyq: Offshore power plants
                Pmhys: Offshore terminals
                Pmhyu: Underwater structures
                    Pmhyuf: Underwater foundations
                    Pmhyup: Underwater pipelines
                    Pmhyut: Underwater tunnels
        Pmn: Pipeline facilities
            Pmnp: Pipelines
                Pmnpp: Pipelines by product carried
                    Pmnppb: Capsule pipelines
                    Pmnppc: Coal pipelines
                    Pmnppg: Gas pipelines
                        Pmnppgn: Natural gas pipelines
                            Pmnppgnm: LNG pipelines
                    Pmnppp: Petroleum pipelines
                    Pmnpps: Slurry pipelines
                    Pmnppu: Sulfur pipelines
                    Pmnppw: Water pipelines
                Pmnpt: Pipelines by location
                    Pmnptu: Underwater pipelines
            Pmns: Pipeline pumping stations
        Pmp: Electric utility facilities
            Pmpp: Electric power plants
                Pmppc: Combined cycle power plants
                Pmppf: Fossil fuel power plants
                Pmppg: Geothermal power plants
                Pmpph: Hydroelectric plants
                Pmppn: Nuclear power plants
                Pmppp: Offshore power plants
                Pmpps: Solar power plants
                Pmppt: Steam power plants
                Pmppu: Tidal power plants
                Pmppv: Thermal power plants
                    Pmppvc: Cooling towers
            Pmpt: Electric power transmission facilities
                Pmptm: Transmission lines
                    Pmptmg: Grids (Transmission lines)
                    Pmptmp: Overhead utility lines
                    Pmptmu: Underground utility lines
                Pmptp: Utility poles
                Pmpts: Electric substations
                Pmptt: Electric transmission towers
            Pmpv: Street lighting
                Pmpvc: Lighting columns
                    Pmpvch: High mast lighting
                Pmpvm: Luminaires
        Pmr: Highway facilities
            Pmrc: Roads
                Pmrcc: Types of roads
                    Pmrccd: Principal types of roads
                        Pmrccdb: Alleys
                        Pmrccde: Expressways
                        Pmrccdf: Freeways
                        Pmrccdh: Highways
                            Pmrccdhb: Arterial highways
                            Pmrccdhc: Depressed highways
                            Pmrccdhd: Divided highways
                        Pmrccds: Streets
                            Pmrccdsc: Cul de sacs
                            Pmrccdsd: Dead end streets
                            Pmrccdsp: One way streets
                    Pmrcce: Types of roads by environment
                        Pmrccef: Forest roads
                        Pmrccem: Mountain roads
                        Pmrccep: Parkways
                        Pmrccer: Rural highways
                        Pmrcces: Scenic highways
                        Pmrcceu: Urban highways
                    Pmrccj: Types of roads by jurisdiction
                        Pmrccjc: County roads
                        Pmrccjf: Federal aid highways
                        Pmrccjj: International roads
                        Pmrccjm: Interstate highways
                        Pmrccjp: Primary highways
                        Pmrccjq: Private roads
                            Pmrccjqd: Driveways
                        Pmrccjr: Public roads
                        Pmrccjs: Secondary roads
                        Pmrccjt: State highways
                        Pmrccjv: Toll roads
                    Pmrcck: Types of roads by number of lanes
                        Pmrcckb: Two lane highways
                        Pmrcckf: Three lane highways
                        Pmrcckm: Four lane highways
                        Pmrcckr: Multilane highways
                    Pmrccn: Types of roads by network
                        Pmrccnb: Access roads
                            Pmrccnbf: Frontage roads
                        Pmrccnd: Approach roads
                        Pmrccnf: Beltways
                        Pmrccnj: Bypasses
                        Pmrccnm: Highway corridors
                        Pmrccnr: Radial highways
                    Pmrccp: Types of roads by purpose
                        Pmrccpb: Automated highways
                        Pmrccpc: Commercial strips
                        Pmrccpe: Experimental roads
                            Pmrccpet: Test tracks
                                Pmrccpetc: Circular test tracks
                        Pmrccpf: Farm roads
                        Pmrccph: Haul roads
                        Pmrccpk: Logging roads
                        Pmrccpp: Recreational roads
                        Pmrccpr: Residential streets
                        Pmrccps: Service roads
                    Pmrccu: Unpaved roads
                        Pmrccue: Earth roads
                        Pmrccug: Gravel roads
                    Pmrccv: Types of roads by traffic volume
                        Pmrccvh: High volume roads
                        Pmrccvm: Low volume roads
                Pmrck: Geometric segments
                    Pmrckc: Highway curves
                        Pmrckct: Transition curves
                    Pmrckg: Highway grades
                        Pmrckgd: Downgrades (Roads)
                        Pmrckgu: Upgrades (Roads)
                Pmrcp: Parts of roads
                    Pmrcpb: Barriers (Roads)
                        Pmrcpbc: Anti glare screens
                        Pmrcpbe: Crash cushions
                            Pmrcpbet: Truck mounted attenuators
                        Pmrcpbg: Guardrails
                            Pmrcpbgt: Guardrail terminals
                            Pmrcpbgv: Guardrail transition sections
                        Pmrcpbm: Medians
                            Pmrcpbmb: Median barriers
                            Pmrcpbmp: Median openings
                        Pmrcpbn: Noise barriers
                    Pmrcpc: Curbs
                    Pmrcpj: Interchanges and intersections
                        Pmrcpjf: Intersections
                            Pmrcpjfc: Types of intersections
                                Pmrcpjfcb: At grade intersections
                                Pmrcpjfcd: Channelized intersections
                                Pmrcpjfcf: Four leg intersections
                                Pmrcpjfcg: Offset intersections
                                Pmrcpjfch: Signalized intersections
                                    Pmrcpjfchi: Isolated intersections
                                Pmrcpjfcj: T intersections
                                Pmrcpjfcm: Traffic circles
                                    Pmrcpjfcmr: Roundabouts
                                Pmrcpjfcp: Three leg intersections
                                Pmrcpjfcr: Unchannelized intersections
                                Pmrcpjfct: Unsignalized intersections
                                Pmrcpjfcv: Y intersections
                            Pmrcpjfr: Intersection elements
                                Pmrcpjfrd: Dilemma zone
                                Pmrcpjfrf: Gore area
                                Pmrcpjfrj: Grade separations
                                    Pmrcpjfrjp: Overpasses
                                    Pmrcpjfrju: Underpasses
                                Pmrcpjfrt: Traffic islands
                        Pmrcpjs: Interchanges
                            Pmrcpjsc: Types of interchanges
                                Pmrcpjscc: Cloverleaf interchanges
                                Pmrcpjscd: Diamond interchanges
                                    Pmrcpjscds: Single point urban interchanges
                                Pmrcpjsct: Trumpet interchanges
                            Pmrcpjsr: Interchange elements
                                Pmrcpjsrm: Merging area
                                Pmrcpjsrr: Ramps (Interchanges)
                                    Pmrcpjsrrf: Off ramps
                                    Pmrcpjsrrn: On ramps
                    Pmrcpm: Traffic lanes
                        Pmrcpma: Approach lanes
                        Pmrcpmb: Auxiliary lanes
                        Pmrcpmc: Bicycle lanes
                        Pmrcpme: Climbing lanes
                        Pmrcpmg: Contraflow lanes
                        Pmrcpmh: Downgrade lanes
                        Pmrcpmi: Express lanes
                        Pmrcpmj: High occupancy vehicle lanes
                            Pmrcpmjb: Bus lanes
                            Pmrcpmjh: High occupancy toll lanes
                        Pmrcpmk: Lane drops
                        Pmrcpml: Managed lanes
                        Pmrcpmm: Median lanes
                        Pmrcpmr: Reversible traffic lanes
                        Pmrcpmt: Speed change lanes
                            Pmrcpmtb: Acceleration lanes
                            Pmrcpmtd: Deceleration lanes
                            Pmrcpmtp: Passing lanes
                        Pmrcpmv: Truck lanes
                        Pmrcpmx: Turning lanes
                            Pmrcpmxm: Left turn lanes
                                Pmrcpmxmt: Two way left turn lanes
                            Pmrcpmxr: Right turn lanes
                    Pmrcpp: Pavements
                        Pmrcppb: Types of pavements
                            Pmrcppbd: Types of pavements by surface load distribution
                                Pmrcppbdf: Flexible pavements
                                Pmrcppbdr: Rigid pavements
                            Pmrcppbm: Types of pavements by material
                                Pmrcppbmb: Asphalt pavements
                                Pmrcppbmd: Asphalt concrete pavements
                                Pmrcppbmf: Bituminous pavements
                                Pmrcppbmh: Bituminous concrete pavements
                                Pmrcppbmj: Brick pavements
                                Pmrcppbmk: Composite pavements
                                Pmrcppbmm: Concrete pavements
                                    Pmrcppbmmn: Precast concrete pavements
                                    Pmrcppbmmp: Prestressed concrete pavements
                                    Pmrcppbmmr: Reinforced concrete pavements
                                        Pmrcppbmmrc: Continuously reinforced concrete pavements
                                    Pmrcppbmms: Roller compacted concrete pavements
                                Pmrcppbmp: Mosaic pavements
                                Pmrcppbms: Soil cement pavements
                                Pmrcppbmw: Wooden pavements
                            Pmrcppbr: Perpetual pavements
                        Pmrcppp: Pavement components
                            Pmrcpppj: Pavement joints
                            Pmrcpppm: Pavement layers
                                Pmrcpppmb: Surface course (Pavements)
                                    Pmrcpppmbb: Binder course
                                    Pmrcpppmbf: Friction course
                                    Pmrcpppmbp: Overlays (Pavements)
                                        Pmrcpppmbpb: Bituminous overlays
                                        Pmrcpppmbpc: Concrete overlays
                                            Pmrcpppmbpcp: Whitetopping
                                    Pmrcpppmbs: Seal coats
                                    Pmrcpppmbw: Wearing course (Pavements)
                                    Pmrcpppmby: Surface course irregularities
                                        Pmrcpppmbyp: Potholes (Pavements)
                                        Pmrcpppmbyr: Ruts (Pavements)
                                Pmrcpppme: Base course (Pavements)
                                    Pmrcpppmeb: Bituminous bases
                                    Pmrcpppmec: Concrete bases
                                    Pmrcpppmeg: Granular bases
                                Pmrcpppmg: Subbase (Pavements)
                                Pmrcpppmr: Subgrade (Pavements)
                    Pmrcpr: Roadside
                        Pmrcprc: Clear zones
                        Pmrcprm: Roadside memorials
                        Pmrcprs: Roadside structures
                            Pmrcprsm: Mailboxes
                    Pmrcps: Road shoulders
                        Pmrcpsp: Paved shoulders
                        Pmrcpsw: Dropoffs (Pavements)
                    Pmrcpw: Weaving sections
            Pmrt: Highway facilities for nonmotorized users
                Pmrtc: Bicycle facilities
                    Pmrtcc: Bicycle crossings
                    Pmrtcg: Bicycle lanes
                    Pmrtcm: Bikeways
                Pmrtp: Pedestrian areas
                    Pmrtpc: Crosswalks
                        Pmrtpcd: School crossings
                        Pmrtpck: Midblock crossings
                        Pmrtpcp: Panda crossings
                        Pmrtpcz: Zebra crossings
                    Pmrtpm: Moving sidewalks
                    Pmrtpp: Pedestrian malls
                    Pmrtps: Sidewalks
                    Pmrtpt: Trails
                    Pmrtpw: Walkways
            Pmru: Highway facilities for motorized users
                Pmrub: Bus and high occupancy vehicle facilities
                    Pmrubg: Bus garages
                    Pmrubm: Bus lanes
                    Pmrubs: Bus stops
                        Pmrubsb: Bus bays
                        Pmrubsk: Farside (Bus stops)
                        Pmrubsn: Nearside (Bus stops)
                        Pmrubss: Bus stop shelters
                    Pmrubt: Bus terminals
                    Pmrubw: Busways
                    Pmruby: High occupancy vehicle lanes
                Pmruj: Inspection stations
                Pmrup: Parking facilities
                    Pmrupg: Parking garages
                        Pmrupgu: Underground parking garages
                    Pmrupm: Parking lots
                Pmruq: Roadside rest areas
                Pmrur: Service stations
                Pmrus: Toll facilities
                    Pmrusb: Toll booths
                    Pmrusp: Toll plazas
                Pmrut: Traffic control centers
                Pmruu: Truck facilities
                    Pmruue: Escape lanes
                        Pmruueb: Arrester beds
                    Pmruuk: Truck lanes
                    Pmruum: Truck loading facilities
                    Pmruus: Truck stops
                    Pmruut: Truck terminals
                    Pmruuw: Weigh stations
                        Pmruuws: Motor vehicle scales
                        Pmruuww: Weigh in motion scales
                Pmruv: Turnouts
        Pmu: Railroad facilities
            Pmuc: Contact wire
                Pmucc: Catenaries (Railroads)
            Pmud: Railroad tracks
                Pmudb: Types of track
                    Pmudbb: Ballastless track
                    Pmudbc: Curved track
                    Pmudbe: Concrete slab track
                    Pmudbf: Double track
                    Pmudbg: Guideways
                    Pmudbh: High speed track
                    Pmudbj: Jointed track
                    Pmudbm: Multiple track
                    Pmudbn: Narrow gage track
                    Pmudbs: Single track
                    Pmudbt: Tangent track
                    Pmudbv: Track panels
                    Pmudbx: Unconventional track
                Pmude: Lines of track
                    Pmudeb: Branch lines
                    Pmudem: Main lines
                Pmudk: Track components
                    Pmudkb: Ballast crib
                    Pmudkd: Crossovers
                    Pmudkh: Frogs (Railroads)
                    Pmudkr: Rail (Railroads)
                        Pmudkrb: Types of railroad rail
                            Pmudkrbb: Curved rail
                            Pmudkrbc: Continuous welded rail
                            Pmudkrbd: Corrugated rail
                            Pmudkrbh: Heat treated rail
                            Pmudkrbr: Reaction rails
                            Pmudkrbs: Steel rails
                            Pmudkrbt: Third rail
                            Pmudkrbw: Welded rail
                        Pmudkrk: Rail components
                            Pmudkrkj: Rail joints
                            Pmudkrkr: Railhead
                    Pmudks: Sidings (Railroads)
                    Pmudkt: Switches (Railroads)
                    Pmudku: Railroad ties
                        Pmudkuc: Concrete ties
                            Pmudkucp: Prestressed concrete ties
                        Pmudkus: Steel ties
                        Pmudkuw: Wood ties
                    Pmudkv: Tie pads
                    Pmudkw: Tie plates
                    Pmudkx: Turnouts
            Pmuj: Railroad grade crossings
                Pmujs: Grade crossing surfaces
            Pmur: Railroad buildings
                Pmurp: Railroad stations
                    Pmurpr: Rail transit stations
                        Pmurprs: Subway stations
                Pmurt: Railroad terminals
                Pmurv: Railroad maintenance facilities
                    Pmurvc: Car shops (Railroads)
                    Pmurvm: Locomotive shops
                    Pmurvw: Wheel shops (Railroads)
            Pmut: Railroad yards
                Pmutc: Classification yards
                    Pmutch: Hump yards
            Pmuy: Rail transit facilities
                Pmuyc: Light rail transit grade crossings
                Pmuyg: Guideways
                    Pmuyge: Line extensions (Rail transit)
                Pmuys: Rail transit stations
                    Pmuyss: Subway stations
    Pt: Structural deterioration and defects
        Pte: Deterioration
            Pteb: Aging (Materials)
            Ptew: Wear
        Ptq: Defects
Q: Vehicles and equipment
    Qb: Vehicles
        Qbd: Ground vehicles
            Qbdb: Rolling stock
            Qbdd: Motor vehicles
                Qbddb: Vehicle fleets
                Qbddf: Trucks
                    Qbddfc: Tractor trailer combinations
                        Qbddfcm: Truck tractors
                        Qbddfct: Trailers
                    Qbddfk: Special purpose trucks
                        Qbddfkd: Delivery vehicles
                        Qbddfkj: Industrial trucks
                            Qbddfkjs: Straddle trucks
                        Qbddfkk: Refrigerator trucks
                        Qbddfkp: Tow trucks
                        Qbddfkr: Dump trucks
                        Qbddfkt: Tank trucks
                        Qbddfkw: Logging trucks
                    Qbddfp: Trucks by motive power
                        Qbddfpd: Diesel trucks
                        Qbddfpe: Electric trucks
                    Qbddft: Trucks by number of axles
                        Qbddftb: Two axle trucks
                        Qbddftc: Three axle trucks
                    Qbddfw: Trucks by weight
                        Qbddfwc: Light trucks
                            Qbddfwcf: Pickup trucks
                        Qbddfwf: Medium trucks
                        Qbddfwh: Heavy duty trucks
                Qbddh: Passenger vehicles
                    Qbddhm: Private passenger vehicles
                        Qbddhmc: Automobiles
                            Qbddhmcc: Automobiles by type
                                Qbddhmccb: Large automobiles
                                Qbddhmccc: Midsize automobiles
                                Qbddhmccd: Compact automobiles
                                Qbddhmccf: Subcompact automobiles
                                Qbddhmcch: Miniature automobiles
                                Qbddhmccm: Station wagons
                                Qbddhmccs: Sports cars
                                Qbddhmcct: Convertibles (Automobiles)
                                Qbddhmccu: Utility vehicles
                                    Qbddhmccus: Sport utility vehicles
                                Qbddhmccx: Foreign automobiles
                            Qbddhmck: Special purpose automobiles
                                Qbddhmckh: Automobiles for the physically handicapped
                                Qbddhmckr: Race cars
                                Qbddhmckt: Rental cars
                            Qbddhmcp: Automobiles by motive power
                                Qbddhmcpe: Electric automobiles
                                Qbddhmcpg: Gas turbine automobiles
                                Qbddhmcph: Hybrid automobiles
                                Qbddhmcps: Steam automobiles
                        Qbddhmm: Two wheeled vehicles
                            Qbddhmmm: Mopeds
                            Qbddhmmq: Motorcycles
                        Qbddhmn: Three wheeled vehicles
                    Qbddhp: Public passenger vehicles
                        Qbddhpb: Buses
                            Qbddhpbk: Special purpose buses
                                Qbddhpbke: Express buses
                                Qbddhpbkf: Feeder buses
                                Qbddhpbkk: School buses
                                Qbddhpbkq: Guided buses
                                Qbddhpbks: Shuttle buses
                                Qbddhpbkt: Transit buses
                                Qbddhpbkv: Tour buses
                            Qbddhpbp: Buses by motive power
                                Qbddhpbpd: Diesel buses
                                Qbddhpbpe: Electric buses
                                    Qbddhpbpet: Trolleybuses
                                Qbddhpbpg: Natural gas buses
                            Qbddhpbw: Buses by size
                                Qbddhpbwb: Minibuses
                                Qbddhpbwd: Small buses
                                Qbddhpbwh: Double deck buses
                                Qbddhpbwj: Articulated buses
                        Qbddhpp: Paratransit vehicles
                            Qbddhpph: High occupancy vehicles
                            Qbddhppj: Jitneys
                            Qbddhppl: Limousines
                            Qbddhppt: Taxicabs
                Qbddk: Special purpose vehicles
                    Qbddkb: All terrain vehicles
                    Qbddkc: Commercial vehicles
                    Qbddkd: Dual mode vehicles
                    Qbddke: Emergency vehicles
                        Qbddkef: Fire vehicles
                        Qbddkem: Ambulances
                    Qbddkh: Farm vehicles
                        Qbddkht: Farm tractors
                    Qbddkj: Intelligent vehicles
                    Qbddkl: Low floor vehicles
                    Qbddkm: Military vehicles
                        Qbddkmb: Autonomous land vehicles
                        Qbddkmc: Combat vehicles
                            Qbddkmct: Tanks (Combat vehicles)
                    Qbddkn: Armored vehicles
                    Qbddkp: Police vehicles
                    Qbddkq: Recreational vehicles
                        Qbddkqc: Camper trucks
                        Qbddkqg: Golf carts
                        Qbddkqt: Travel trailers
                    Qbddkr: Tracked vehicles
                    Qbddkt: Towing vehicles
                    Qbddku: Towed vehicles
                    Qbddkw: Snowmobiles
                    Qbddkx: Test vehicles
                        Qbddkxd: Impact sleds
                            Qbddkxdr: Rocket sleds
                        Qbddkxj: Instrumented vehicles
                            Qbddkxjb: Experimental vehicles
                            Qbddkxjp: Probe vehicles
                        Qbddkxs: Safety vehicles
                        Qbddkxw: Skid trailers
                        Qbddkxy: Vans
                    Qbddky: Zero emission vehicles
                Qbddp: Vehicles by motive power
                    Qbddpe: Electric vehicles
                        Qbddpef: Fuel cell vehicles
                    Qbddph: Hybrid vehicles
                    Qbddps: Solar powered vehicles
                Qbddv: Vehicles by speed
                    Qbddvf: High speed vehicles
                    Qbddvs: Slow moving vehicles
                Qbddw: Vehicles by weight
                    Qbddwd: Light vehicles
                    Qbddwh: Heavy vehicles
                    Qbddwk: Heavy duty vehicles
            Qbdf: Horse drawn vehicles
            Qbdh: Human powered vehicles
                Qbdhb: Bicycles
                Qbdhc: Tricycles
                Qbdhh: Wheelchairs
                Qbdhr: Rickshaws
                Qbdhs: Scooters
                Qbdhu: In-line skates
        Qbf: Railroad trains
            Qbff: Freight trains
            Qbfh: Passenger trains
            Qbfj: Multiple unit trains
            Qbfm: Train components
                Qbfmc: Locomotives
                    Qbfmcc: Types of locomotives
                        Qbfmccm: Multiple unit locomotives
                        Qbfmccp: Slave locomotives
                        Qbfmccs: Switching locomotives
                    Qbfmcp: Locomotives by motive power
                        Qbfmcpd: Diesel locomotives
                        Qbfmcpe: Diesel electric locomotives
                        Qbfmcph: Diesel hydraulic locomotives
                        Qbfmcpk: Electric locomotives
                        Qbfmcpp: Gas turbine locomotives
                        Qbfmcpq: Dual powered locomotives
                        Qbfmcps: Steam locomotives
                Qbfmk: Railroad cars
                    Qbfmkc: Cabooses
                    Qbfmkf: Freight cars
                        Qbfmkfc: Covered freight cars
                            Qbfmkfca: Automobile rack cars
                            Qbfmkfcb: Box cars
                            Qbfmkfch: Covered hopper cars
                            Qbfmkfcr: Refrigerator cars
                            Qbfmkfct: Tank cars
                        Qbfmkfg: Open top cars
                            Qbfmkfgc: Container cars
                            Qbfmkfgf: Flat cars
                            Qbfmkfgg: Gondola cars
                            Qbfmkfgh: Hopper cars
                        Qbfmkfx: Mine cars
                    Qbfmkh: Passenger cars
                        Qbfmkhb: Intercity passenger cars
                        Qbfmkhc: Commuter cars
                            Qbfmkhcd: Double deck commuter cars
                        Qbfmkhu: Rapid transit cars
                        Qbfmkhw: Sleeping cars
                    Qbfmkj: Rail motorcars
                    Qbfmkk: Maintenance of way cars
                        Qbfmkkt: Inspection cars
                    Qbfmkm: Multiple unit cars
                        Qbfmkmd: Diesel multiple unit cars
                        Qbfmkme: Electric multiple unit cars
                    Qbfmkt: Railroad cars by type
                        Qbfmktb: Two axle cars
                        Qbfmktd: Four axle cars
                        Qbfmktj: Articulated cars
                        Qbfmktk: High capacity cars
                        Qbfmktm: Aluminum cars
            Qbfp: Trains by motive power
                Qbfpe: Electric trains
                Qbfpt: Turbotrains
            Qbft: Streetcars
                Qbftc: Cable cars
                Qbftt: Trolley cars
            Qbfx: Special trains
                Qbfxb: Railbuses
                Qbfxg: Tracked air cushion vehicles
                Qbfxh: High speed trains
                Qbfxj: Light rail vehicles
                Qbfxm: Magnetic levitation vehicles
                Qbfxv: Crewless trains
                Qbfxx: Test trains
                Qbfxy: Tilting trains
        Qbh: Ships
            Qbhd: Merchant vessels
                Qbhdb: Merchant marine
                Qbhdf: Cargo ships
                    Qbhdfb: Bulk carriers
                        Qbhdfbg: Combination carriers
                            Qbhdfbgo: Ore bulk oil carriers
                        Qbhdfbk: Dry bulk carriers
                            Qbhdfbko: Ore carriers
                        Qbhdfbm: Tankers
                            Qbhdfbmc: Chemical tankers
                            Qbhdfbmp: Oil tankers
                                Qbhdfbmpw: Supertankers
                                Qbhdfbmpy: Very large crude carriers
                    Qbhdfj: Barge carriers
                    Qbhdfk: Containerships
                    Qbhdfm: General cargo ships
                    Qbhdfp: Roll on roll off ships
                    Qbhdfr: Refrigerated ships
                    Qbhdfu: Cargo submarines
                Qbhdh: Passenger ships
                    Qbhdhc: Cruise ships
                    Qbhdhm: Ocean liners
                    Qbhdht: Ferries
            Qbhe: Pleasure craft
                Qbheb: Aquaplanes
                Qbhex: Yachts
            Qbhf: Feeder vessels
                Qbhfs: Offshore supply boats
            Qbhk: Special purpose ships
                Qbhkd: Drilling ships
                Qbhkp: Survey vessels
                Qbhkr: Research ships
                    Qbhkrm: Oceanographic vessels
                Qbhks: Icebreakers
                    Qbhksn: Nuclear powered icebreakers
                Qbhkt: Tugboats
                    Qbhktm: Ocean going tugs
                    Qbhktp: Towboats
            Qbhn: Inland waterways vessels
            Qbho: Ships by ownership
                Qbhog: Government vessels
                Qbhom: Military vessels
                    Qbhoma: Aircraft carriers
                    Qbhomb: Submarines
                    Qbhomf: Cruisers
                    Qbhomh: Frigates
                    Qbhomj: Destroyers
                    Qbhomm: Landing craft
            Qbhp: Ships by motive power
                Qbhpj: Waterjet propelled craft
                Qbhpn: Nuclear powered ships
                Qbhpw: Sailing ships
                Qbhpy: Steamships
            Qbhs: Boats
                Qbhsh: Hydrofoil boats
                Qbhsj: Hydroplanes
                Qbhss: Surface effect ships
                Qbhsw: Work boats
                    Qbhswc: Heavy lift vessels
                    Qbhswf: Fire boats
                    Qbhswh: Fishing vessels
                    Qbhswm: Lifeboats
                        Qbhswmr: Life rafts
                            Qbhswmri: Inflatable life rafts
                    Qbhswp: Patrol boats
                    Qbhswq: Pontoon boats
                    Qbhsws: Supply vessels
                        Qbhswso: Offshore support vessels
                        Qbhswsp: Tug supply vessels
                        Qbhswst: Tenders
            Qbht: Barges
                Qbhtm: LASH barges
                Qbhtp: Pusher barges
                Qbhtt: Tank barges
                Qbhtu: Towed barges
            Qbhu: Underwater vehicles
                Qbhud: Deep submergence vehicles
                Qbhus: Semisubmersibles
                Qbhuu: Submersibles
            Qbhv: Multi hulled ships
                Qbhvt: Twin hulled ships
                    Qbhvtc: Catamarans
                Qbhvw: SWATH ships
            Qbhw: Ships by size
                Qbhwb: Full bodied ships
                Qbhws: Small ships
                Qbhww: Deep draft ships
                Qbhwx: Shallow draft ships
            Qbhx: High performance surface ships
                Qbhxf: High speed craft
        Qbk: Aircraft
            Qbkf: Transport aircraft
                Qbkff: Cargo aircraft
                Qbkfj: Jet transports
                Qbkfr: Regional jets
                Qbkfs: Supersonic transport planes
            Qbkh: Passenger aircraft
                Qbkha: Air ambulances
                Qbkhc: Commuter aircraft
            Qbkk: Utility aircraft
                Qbkkt: Training aircraft
                    Qbkktj: Jet training planes
            Qbkm: Aircraft by type of lift
                Qbkmf: Airplanes
                Qbkmh: Tilt wing aircraft
                Qbkmj: STOL aircraft
                Qbkmk: VTOL aircraft
                    Qbkmkp: Tiltrotor aircraft
                    Qbkmks: V/STOL aircraft
                Qbkmr: Rotary wing aircraft
                    Qbkmrh: Helicopters
                Qbkmw: Lighter than air craft
                    Qbkmwb: Balloons
                    Qbkmwd: Airships
            Qbko: Aircraft by ownership
                Qbkoc: Civil aircraft
                Qbkom: Military aircraft
                    Qbkomf: Attack aircraft
                        Qbkomff: Jet fighters
                    Qbkomh: Drone aircraft
                        Qbkomhr: Remotely piloted aircraft
                    Qbkomk: Guided missiles
                    Qbkomm: Army aircraft
                    Qbkomn: Naval aircraft
                Qbkop: General aviation aircraft
                    Qbkopc: Business aircraft
                    Qbkopp: Private aircraft
            Qbkp: Aircraft by motive power
                Qbkph: Human powered aircraft
                Qbkpj: Jet propelled aircraft
                Qbkpp: Propeller driven aircraft
                    Qbkppg: Turboprop aircraft
                Qbkpw: Wind powered aircraft
            Qbks: Aircraft by speed
                Qbksb: Subsonic aircraft
                Qbksf: Supersonic aircraft
                Qbksh: Hypersonic aircraft
            Qbkw: Aircraft by size
                Qbkwf: Small aircraft
                    Qbkwfu: Ultralight aircraft
                Qbkwn: Narrow body aircraft
                Qbkww: Wide body aircraft
            Qbky: Seaplanes
        Qbn: Spacecraft
            Qbnc: Artificial satellites
            Qbnl: Launch vehicles
            Qbns: Space shuttles
            Qbnu: Space stations
        Qbq: Amphibious vehicles
            Qbqg: Air cushion vehicles
    Qc: Vehicle characteristics
        Qcc: Vehicle capacity
        Qcf: Vehicle fitness
            Qcfd: Airworthiness
            Qcfm: Crashworthiness
            Qcfp: Driveability
            Qcfs: Seaworthiness
        Qch: Handling characteristics
            Qcht: Turning radius
        Qcm: Maneuverability
        Qcp: Vehicle performance
            Qcpb: Braking performance
            Qcpd: Drawbar pull
            Qcph: Horsepower
            Qcpr: Range (Vehicles)
            Qcpt: Riding qualities
        Qcs: Vehicle size
            Qcsm: Metacentric height
            Qcsw: Wheel base
        Qcw: Vehicle weight
            Qcwg: Gross weight
                Qcwgg: Gross vehicle weight
            Qcwu: Unsprung weight
    Qd: Vehicle dynamics
        Qdb: Flight
            Qdbc: Flight characteristics
                Qdbca: Angle of attack
                Qdbcb: Airspeed
                Qdbcg: Ground speed
                    Qdbcgw: Wind factor (Air navigation)
                Qdbct: Flight time
            Qdbd: Flight dynamics
                Qdbdb: Aerodynamic lift
                    Qdbdbm: Lift drag ratio
                Qdbde: Aerodynamic stability
                    Qdbdeh: Directional stability
                    Qdbdeq: Dynamic stability
                Qdbdf: Attitude (Flight dynamics)
                Qdbdh: Downwash
                Qdbdj: Flutter (Aeronautics)
                Qdbdk: Ground effect
                Qdbdn: Pitch (Dynamics)
                    Qdbdnm: Pitching moment
                Qdbdr: Stall
                Qdbdt: Thrust
                    Qdbdtb: Blade loading
                Qdbdu: Trim (Aeronautics)
                Qdbdw: Wing loading
                Qdbdx: Yaw
            Qdbp: Flight paths
                Qdbpb: Approach
                Qdbpf: Climbing flight
                Qdbpk: Cruising flight
                Qdbpp: Descent
        Qdm: Motor vehicle dynamics
            Qdmb: Axle loads
                Qdmbt: Tandem axle loads
                Qdmbw: Wheel loads
            Qdmp: Offtracking
            Qdms: Skidding
            Qdmt: Tire mechanics
                Qdmtp: Tire pressure
                Qdmtt: Tire forces
            Qdmv: Trailer swing
            Qdmx: Wheel slip
        Qdr: Train track dynamics
            Qdrh: Hunting (Dynamics)
            Qdrm: L/V ratio
            Qdrr: Rocking
        Qds: Ship motion
            Qdsb: Dynamic stability
            Qdsd: Heaving (Ship motion)
            Qdsg: Heeling
            Qdsj: Pitch (Dynamics)
                Qdsjp: Pitching moment
            Qdsm: Rolling
            Qdsp: Slamming
            Qdsq: Surging
            Qdst: Swaying
            Qdsy: Yaw
    Qp: Vehicle components
        Qpb: Vehicle bodies
            Qpba: Vehicle body parts
                Qpbac: Vehicle front end
                    Qpbacb: Bows
                Qpbai: Vehicle interiors
                Qpbam: Vehicle rear end
                    Qpbams: Sterns
                    Qpbamt: Tails (Aircraft)
                Qpbas: Vehicle sides
                    Qpbasn: Nearside
                    Qpbaso: Offside
                    Qpbasp: Port side
                    Qpbass: Starboard side
                Qpbau: Underbodies
                    Qpbaub: Bilges
                    Qpbaud: Double bottoms
                Qpbax: Vehicle roofs
            Qpbb: Bodies of specific vehicles
                Qpbbb: Airframes
                    Qpbbbk: Airfoils
                        Qpbbbkd: Elevators (Airplanes)
                        Qpbbbkf: Fins (Aircraft)
                        Qpbbbkm: Leading edges
                        Qpbbbkt: Trailing edges
                        Qpbbbkw: Wings (Aircraft)
                    Qpbbbr: Fuselages
                Qpbbd: Bluff bodies
                Qpbbm: Motor vehicle bodies
                Qpbbs: Ship bodies
                    Qpbbsh: Hulls
                        Qpbbshp: Planing hulls
                    Qpbbsm: Hydrofoils
                        Qpbbsms: Supercavitating hydrofoils
            Qpbc: Vehicle body components
                Qpbcb: Bumpers
                Qpbcd: Doors (Vehicles)
                    Qpbcdh: Hatch covers
                Qpbce: Door latches
                Qpbcf: Door handles
                Qpbch: Hoods
                Qpbcj: Aerodynamic features (Vehicle body components)
                    Qpbcjf: Fairings
                    Qpbcjs: Spoilers
                Qpbcn: Fenders
                Qpbct: Trunks (Vehicles)
                Qpbcw: Windows (Vehicles)
                    Qpbcws: Side windows
                    Qpbcwx: Windshields
        Qpe: Vehicle compartments
            Qpec: Crew compartments
                Qpecb: Bridges (Ships)
                Qpecc: Cabs (Vehicle compartments)
                Qpecf: Flight decks
                    Qpecfc: Cockpits
            Qpep: Passenger compartments
                Qpepb: Aircraft cabins
            Qpes: Cargo compartments
                Qpesh: Holds (Vehicles)
            Qpeu: Engine compartments
                Qpeun: Nacelles
            Qpey: Vehicle compartment components
                Qpeyj: Instrument panels
                    Qpeyjj: Indicators (Instruments)
                Qpeyp: Pedals
                Qpeys: Seats
                    Qpeysb: Types of seats
                        Qpeysbe: Ejection seats
                        Qpeysbf: Front seats
                        Qpeysbr: Rear seats
                    Qpeysy: Parts of seats
                        Qpeysyb: Seat backs
                        Qpeysyh: Headrests
        Qpg: Vehicle frames
            Qpgc: Chassis
            Qpgy: Structural components of specific vehicles
                Qpgyb: Aircraft structural components
                    Qpgybb: Ribs (Aircraft)
                Qpgyr: Railcar structural components
                    Qpgyrt: Car trucks (Railroads)
                    Qpgyrw: Wheelsets (Railroads)
                        Qpgyrwr: Car wheels (Railroads)
                Qpgys: Ship structural components
                    Qpgysb: Bulkheads (Ships)
                    Qpgysd: Decks (Ships)
                    Qpgyse: Deckhouses
                    Qpgysk: Keels
                    Qpgysp: Plating (Ships)
                    Qpgyss: Skegs
                    Qpgyst: Stems (Ships)
        Qph: Vehicle push devices
            Qphb: Axles
            Qphd: Driving wheels
            Qphp: Propellers
                Qphpb: Types of propellers
                    Qphpbb: Contrarotating propellers
                    Qphpbd: Controllable pitch propellers
                    Qphpbg: Cycloidal propellers
                    Qphpbj: Ducted propellers
                    Qphpbn: Screw propellers
                    Qphpbp: Shrouded propellers
                    Qphpbr: Steerable propellers
                    Qphpbs: Supercavitating propellers
                    Qphpbv: Variable pitch propellers
                Qphpy: Propeller components
                    Qphpyb: Propeller blades
                    Qphpys: Propeller shafts
            Qphr: Rotors
                Qphrb: Rotor blades
        Qpi: Suspension systems
            Qpib: Active suspension systems
            Qpid: Air suspension systems
            Qpif: Front suspension systems
            Qpih: Rear suspension systems
            Qpim: Magnetic levitation
            Qpiy: Suspension system components
                Qpiyb: Ballast (Ships)
                Qpiyc: Ballast tanks
                Qpiyg: Pylons
                Qpiyn: Shock absorbers
                Qpiyp: Snubbers
                Qpiyr: Springs (Vehicles)
                    Qpiyrd: Air springs
                Qpiyt: Stabilizers
        Qpj: Steering systems
            Qpjf: Four wheel steering
            Qpjp: Power steering
            Qpjy: Steering components
                Qpjyb: Ailerons
                Qpjyf: Flaps (Aircraft)
                Qpjyg: Flaperons
                Qpjyh: Handlebars
                Qpjyq: Rudders
                Qpjyr: Sails
                Qpjys: Steering columns
                Qpjyt: Steering gears
                Qpjyu: Steering wheels
                Qpjyw: Thrusters
                    Qpjywb: Bow thrusters
        Qpk: Brakes
            Qpkb: Types of brakes
                Qpkbc: Air brakes
                Qpkbe: Antilock brake systems
                Qpkbj: Disc brakes
                Qpkbm: Eddy current brakes
                Qpkbp: Electric brakes
                Qpkbr: Friction brakes
                Qpkbt: Hydraulic brakes
                Qpkbw: Power brakes
                Qpkbx: Auxiliary brakes
                    Qpkbxe: Emergency brakes
                    Qpkbxp: Parking brakes
            Qpky: Brake components
                Qpkyb: Brake discs
                Qpkyd: Brake drums
                Qpkyf: Brake fluids
                Qpkyk: Brake linings
                Qpkym: Brake lines
                Qpkyp: Brake pads
                Qpkyr: Brake pedals
                Qpkys: Brake shoes
        Qpm: Tires and wheels
            Qpmt: Tires
                Qpmtb: Types of tires
                    Qpmtbp: Types of tires by ply
                        Qpmtbpb: Belted tires
                        Qpmtbpe: Bias ply tires
                        Qpmtbpr: Radial ply tires
                    Qpmtbr: Retreaded tires
                    Qpmtbs: Snow tires
                    Qpmtbt: Studded tires
                Qpmty: Tire components
                    Qpmtyc: Tire cords
                    Qpmtyq: Tire sidewalls
                    Qpmtys: Tire studs
                    Qpmtyt: Tire treads
            Qpmw: Wheels
                Qpmwr: Wheel rims
            Qpmy: Landing gear
                Qpmys: Skids
                Qpmyu: Undercarriages
        Qpn: Fuel systems
            Qpnc: Carburetion
            Qpnf: Fuel injection
                Qpnfb: Air injection systems
                Qpnfe: Electronic fuel injection
            Qpny: Fuel system components
                Qpnyc: Carburetors
                Qpnyf: Fuel regulating devices
                    Qpnyfb: Accelerators (Devices)
                    Qpnyfc: Chokes
                    Qpnyff: Cruise control
                    Qpnyft: Throttles
                Qpnyn: Fuel storage and delivery devices
                    Qpnynf: Fuel filters
                    Qpnynj: Fuel injectors
                    Qpnynp: Fuel pumps
                    Qpnynt: Fuel tanks
                    Qpnynv: Intake valves
        Qpo: Power trains
            Qpob: Vehicle drive systems
                Qpobb: Four wheel drive
                Qpobf: Front wheel drive
                Qpobr: Rear wheel drive
                Qpobw: Electric drives
            Qpox: Power train components
                Qpoxc: Clutches
                Qpoxd: Drivelines
                    Qpoxdd: Drive shafts
                    Qpoxdu: Universal joints
                Qpoxg: Gears
                    Qpoxgd: Differentials (Gears)
                    Qpoxge: Epicyclic gears
                    Qpoxgp: Planetary gear trains
                    Qpoxgs: Reduction gears
                    Qpoxgy: Gear components
                        Qpoxgys: Gearshifts
                        Qpoxgyt: Gear teeth
                Qpoxt: Transmissions
                    Qpoxtb: Automatic transmissions
                    Qpoxtc: Continuously variable transmissions
                    Qpoxth: Hydraulic transmissions
                    Qpoxtm: Manual transmissions
        Qpp: Vehicle power plants
            Qppb: Auxiliary power units
        Qpq: Occupant protection devices
            Qpqr: Restraint systems
                Qpqrm: Manual safety belts
                    Qpqrmk: Knee restraints
                    Qpqrmp: Seat belts
                    Qpqrmt: Shoulder harnesses
                    Qpqrmu: Three point restraint systems
                Qpqrp: Passive restraint systems
                    Qpqrpb: Air bags
                        Qpqrpbs: Side air bags
                    Qpqrpd: Automatic seat belts
                    Qpqrpp: Deployable head restraints
                Qpqry: Child restraint systems
                    Qpqryc: Child safety seats
                        Qpqrycb: Booster seats
            Qpqt: Roll bars
            Qpqv: Vehicle padding
        Qpu: Vehicle electrical systems
            Qpuh: Audible warning devices in vehicles
                Qpuhh: Horns
                Qpuhs: Sirens
            Qpum: Vehicle lighting
                Qpumb: Vehicle lighting systems
                    Qpumbj: Interior lighting
                    Qpumbr: Rear lighting
                    Qpumbs: Side lighting
                Qpumx: Vehicle lighting devices
                    Qpumxb: Brake lamps
                        Qpumxbh: High mounted brake lamps
                    Qpumxd: Daytime running lamps
                    Qpumxh: Headlamps
                        Qpumxhf: Fog lamps
                        Qpumxhh: High beamed headlamps
                        Qpumxhm: Low beamed headlamps
                    Qpumxs: Taillamps
                    Qpumxt: Turn signals
            Qpup: Pantographs
        Qpv: Vehicle electronics
        Qpw: Emission control systems
            Qpwp: Positive crankcase ventilation systems
            Qpwx: Exhaust system components
                Qpwxb: Air injection reactors
                Qpwxe: Exhaust manifolds
                Qpwxf: Exhaust pipes
                Qpwxm: Mufflers
            Qpwy: Emission control devices
                Qpwyb: Afterburners
                Qpwyc: Catalytic converters
        Qpy: Vehicle accessories
            Qpyb: Antitheft devices
            Qpye: Event data recorders
            Qpym: License plates
            Qpys: Splash guard
            Qpyt: Tire chains
            Qpyu: Vehicle identification numbers
            Qpyv: Vehicle viewing aids
                Qpyvp: Periscopes
                Qpyvr: Rearview mirrors
            Qpyw: Windshield wipers
            Qpyx: Windshield washers
    Qt: Equipment
        Qtb: Types of equipment
            Qtba: Acoustic equipment
                Qtbab: Acoustic generators
                    Qtbabe: Electroacoustic transducers
                Qtbad: Amplifiers
                Qtbag: In vehicle annunciators
                Qtbam: Microphones
                Qtbap: Public address systems
                Qtbat: Tape recorders
            Qtbc: Electrical equipment
                Qtbcb: Battery chargers
                Qtbcc: Brushes (Electricity)
                Qtbcd: Buses (Electricity)
                Qtbce: Capacitors
                Qtbcf: Circuit breakers
                    Qtbcfc: Choppers (Electricity)
                Qtbcg: Converters (Electricity)
                    Qtbcgf: Frequency converters
                    Qtbcgq: Static converters
                    Qtbcgs: Synchronous converters
                Qtbch: Electric cables
                Qtbci: Electric circuits
                    Qtbcin: Rectifiers
                    Qtbcir: Regenerators
                    Qtbcit: Thermistors
                Qtbcj: Electric controllers
                Qtbck: Electric generators
                    Qtbckh: Homopolar generators
                Qtbcm: Electrodes
                    Qtbcme: Electrolytic cells
                Qtbcn: Insulators (Electricity)
                Qtbcp: Inverters
                Qtbcq: Modules (Electricity)
                Qtbcr: Relays (Electricity)
                Qtbcs: Resistors
                Qtbct: Sleeves (Electricity)
                Qtbcu: Sockets (Electricity)
                Qtbcv: Stators
                Qtbcw: Switches (Electricity)
                    Qtbcwf: Flashers
                    Qtbcws: Spark gaps
                Qtbcx: Vibrators (Electricity)
                Qtbcy: Voltage regulators
            Qtbe: Electronic equipment
                Qtbea: Analog to digital converters
                Qtbeb: Charge coupled devices
                Qtbec: Cryogenic devices
                Qtbed: Dampers (Electronics)
                Qtbee: Diodes
                    Qtbeem: Light emitting diodes
                Qtbef: Electron tubes
                    Qtbefc: Cathode ray tubes
                    Qtbefv: Vacuum tubes
                Qtbeh: Electronic components
                Qtbei: Electronic controllers
                    Qtbeip: PID controllers
                Qtbej: Integrated circuits
                    Qtbejm: Microwave integrated circuits
                Qtbem: Microwave devices
                Qtbeo: Millimeter wave devices
                Qtbep: Pulse generators
                Qtbeq: Semiconductor devices
                    Qtbeqc: CMOS devices
                Qtbes: Solid state devices
                Qtbet: Transistors
            Qtbf: Electromagnetic devices
                Qtbfb: Coaxial cables
                Qtbfd: Coils (Electromagnetism)
                Qtbff: Commutators
                Qtbfm: Magnets
                    Qtbfme: Electromagnets
                        Qtbfmes: Superconducting magnets
                    Qtbfmp: Permanent magnets
                Qtbfp: Photocells
                Qtbfs: Solenoids
                Qtbfu: Transformers
                    Qtbfuc: Autotransformers
                Qtbfw: Waveguides
            Qtbh: Hydraulic equipment
                Qtbhd: Deflectors
                Qtbhe: Electrohydraulic mechanisms
            Qtbm: Machines
                Qtbmb: Types of machines
                    Qtbmbb: Auxiliary power plants
                    Qtbmbc: Compressors
                        Qtbmbcb: Air compressors
                    Qtbmbe: Engines
                        Qtbmbeb: Types of engines
                            Qtbmbebb: Air engines
                            Qtbmbebd: Engines by cycle
                                Qtbmbebdb: Two stroke cycle engines
                                Qtbmbebdf: Four stroke cycle engines
                            Qtbmbebe: External combustion engines
                                Qtbmbebem: Rankine engines
                                Qtbmbebes: Steam engines
                                Qtbmbebeu: Stirling engines
                            Qtbmbebh: Heat engines
                            Qtbmbebj: Internal combustion engines
                                Qtbmbebjb: Compression ignition engines
                                Qtbmbebjd: Diesel engines
                                    Qtbmbebjdm: Marine diesel engines
                                Qtbmbebjg: Gasoline engines
                                Qtbmbebjn: Otto cycle engines
                                Qtbmbebjp: Piston engines
                                Qtbmbebjr: Rotary engines
                                Qtbmbebjs: Spark ignition engines
                                Qtbmbebjt: Stratified charge engines
                                Qtbmbebjw: Wankel engines
                            Qtbmbebk: Jet engines
                                Qtbmbebkp: Pulsejet engines
                                Qtbmbebkr: Ramjet engines
                            Qtbmbebt: Turbine engines
                                Qtbmbebtf: Turbofan engines
                                    Qtbmbebtfm: Lift fans
                                Qtbmbebtj: Turbojet engines
                                Qtbmbebtp: Turboprop engines
                        Qtbmber: Engine components
                            Qtbmberc: Engine cooling systems
                                Qtbmbercb: Engine air cooling systems
                                    Qtbmbercbf: Fans
                                    Qtbmbercbg: Fan belts
                                Qtbmbercw: Engine water cooling systems
                                    Qtbmbercwr: Radiators
                                        Qtbmbercwrc: Radiator caps
                                    Qtbmbercww: Water pumps
                            Qtbmbere: Engine electrical components
                                Qtbmbereb: Alternators
                                Qtbmberec: Condensers
                                Qtbmberef: Distributors (Engines)
                                Qtbmbereg: Engine regulators
                                Qtbmberej: Engine starters
                                Qtbmberen: Generators
                                Qtbmbereq: Ignition systems
                                    Qtbmbereqj: Ignition coils
                                    Qtbmbereqr: Alcohol ignition interlock devices
                                    Qtbmbereqs: Ignition seat belt interlocks
                                    Qtbmberequ: Spark plugs
                            Qtbmberk: Engine lubrication devices
                                Qtbmberkp: Oil filters
                                Qtbmberkr: Oil pumps
                            Qtbmberm: Engine mechanical components
                                Qtbmbermb: Cams
                                Qtbmbermd: Camshafts
                                Qtbmbermf: Combustors
                                    Qtbmbermfc: Combustion chambers
                                Qtbmbermg: Connecting rods
                                Qtbmbermh: Crankcases
                                Qtbmbermj: Crankshafts
                                Qtbmbermm: Engine bearings
                                Qtbmbermn: Engine cylinders
                                    Qtbmbermnb: Cylinder blocks
                                    Qtbmbermnh: Cylinder heads
                                Qtbmbermp: Engine mounts
                                Qtbmbermr: Flywheels
                                Qtbmbermt: Manifolds
                                Qtbmbermv: Pistons (Engines)
                                    Qtbmbermvr: Piston rings
                                Qtbmbermw: Superchargers
                                    Qtbmbermwx: Turbochargers
                                Qtbmbermx: Thrust reversers
                                Qtbmbermy: Valves
                                    Qtbmbermye: Exhaust valves
                        Qtbmbex: Engine operation
                            Qtbmbexd: Engine balance
                            Qtbmbexg: Engine cycle
                            Qtbmbexm: Engine displacement
                            Qtbmbexp: Engine efficiency
                            Qtbmbexr: Engine idling
                            Qtbmbexs: Engine knock
                            Qtbmbexv: Engine performance
                    Qtbmbm: Motors
                        Qtbmbmb: Alternating current motors
                        Qtbmbmd: Direct current motors
                        Qtbmbmj: Induction motors
                        Qtbmbmm: Linear motors
                            Qtbmbmmm: Linear induction motors
                        Qtbmbmp: Reversible motors
                        Qtbmbms: Synchronous motors
                        Qtbmbmt: Asynchronous motors
                        Qtbmbmw: Three phase motors
                    Qtbmbp: Pumps
                        Qtbmbpc: Centrifugal pumps
                        Qtbmbpf: Fuel pumps
                        Qtbmbpj: Jet pumps
                            Qtbmbpje: Ejectors
                        Qtbmbpm: Mud pumps
                        Qtbmbpp: Oil pumps
                        Qtbmbps: Suction pumps
                        Qtbmbpu: Sump pumps
                        Qtbmbpw: Waterjets
                    Qtbmbt: Turbines
                        Qtbmbtg: Gas turbines
                        Qtbmbtk: Hydraulic turbines
                        Qtbmbtm: Steam turbines
                Qtbmy: Machinery
                    Qtbmyd: Bearings
                        Qtbmyda: Antifriction bearings
                        Qtbmydg: Gas bearings
                        Qtbmydj: Journal bearings
                            Qtbmydjb: Journal boxes
                        Qtbmyds: Shaft bearings
                            Qtbmydsr: Roller bearings
                        Qtbmydt: Thrust bearings
                    Qtbmyh: Blades (Machinery)
                        Qtbmyhv: Vanes (Machinery)
                    Qtbmyj: Fittings
                    Qtbmym: Governors (Devices)
                    Qtbmyq: Shafts (Machinery)
                        Qtbmyqc: Cardan shafts
                    Qtbmyt: Torque converters
                    Qtbmyx: Valves
                        Qtbmyxd: Dampers
                        Qtbmyxp: Pressure relief valves
                        Qtbmyxv: Safety valves
            Qtbn: Nuclear reactors
                Qtbnb: Types of nuclear reactors
                    Qtbnbt: Thermal reactors
                    Qtbnbw: Water cooled reactors
                Qtbnp: Nuclear reactor components
                    Qtbnpc: Nuclear reactor cores
                    Qtbnpf: Fuel elements
            Qtbp: Optical devices
                Qtbpm: Lasers
                Qtbpp: Lenses (Optics)
                    Qtbppc: Contact lenses
                    Qtbppe: Eyeglasses
                Qtbps: Mirrors
                    Qtbpsc: Convex mirrors
                    Qtbpsp: Plane mirrors
                Qtbpt: Night vision devices
                Qtbpu: Optical systems
            Qtbr: Pneumatic equipment
            Qtbs: Portable equipment
        Qtp: Equipment by end use
            Qtpa: Agricultural equipment
                Qtpap: Plows (Agriculture)
            Qtpb: Construction and maintenance equipment
                Qtpbc: Construction equipment
                    Qtpbcb: Compactors
                        Qtpbcbr: Rollers
                            Qtpbcbrr: Road rollers
                                Qtpbcbrrt: Tandem rollers
                            Qtpbcbrs: Sheepsfoot rollers
                    Qtpbce: Crushers
                    Qtpbcg: Drilling machines
                        Qtpbcgc: Cable systems
                    Qtpbcj: Excavating equipment
                        Qtpbcjb: Backhoes
                        Qtpbcjc: Crawler tractors
                            Qtpbcjcb: Bulldozers
                        Qtpbcjf: Draglines
                        Qtpbcjm: Dredges
                    Qtpbck: Graders
                    Qtpbcm: Mixers
                        Qtpbcmc: Concrete mixers
                        Qtpbcmp: Pug mills
                    Qtpbcp: Pile hammers
                    Qtpbcr: Roadbuilding machinery
                        Qtpbcrp: Pavers
                            Qtpbcrps: Slip form pavers
                        Qtpbcrr: Road rollers
                        Qtpbcrs: Screeds
                    Qtpbcs: Spreaders
                    Qtpbct: Tunneling machines
                        Qtpbctb: Tunnel borers
                    Qtpbcv: Vibratory equipment
                Qtpbm: Maintenance equipment
                    Qtpbmd: Deicers (Equipment)
                    Qtpbmm: Mowers
                    Qtpbmq: Shadow vehicles
                    Qtpbms: Snowplows
            Qtpe: Cleaning equipment
                Qtped: Air cleaners
                    Qtpedb: Air filters
                    Qtpedc: Cyclone separators
                    Qtpedd: Dust filters
                    Qtpede: Electrostatic precipitators
                    Qtpeds: Scrubbers
                Qtpep: Oil recovery equipment
                    Qtpepp: Oil booms
                Qtpes: Sweepers
                Qtpev: Vacuum cleaners
            Qtpf: Energy storage devices
                Qtpfb: Electric batteries
                    Qtpfbb: Batteries by chemical elements
                        Qtpfbba: Aluminum air batteries
                        Qtpfbbj: Lead acid batteries
                        Qtpfbbm: Lithium batteries
                            Qtpfbbms: Lithium sulfur batteries
                        Qtpfbbn: Nickel batteries
                            Qtpfbbnc: Nickel cadmium batteries
                            Qtpfbbnj: Nickel iron batteries
                            Qtpfbbny: Nickel zinc batteries
                        Qtpfbbs: Sodium sulfur batteries
                        Qtpfbby: Zinc chloride batteries
                    Qtpfbp: Primary batteries
                    Qtpfbs: Storage batteries
                    Qtpfby: Battery parts
                        Qtpfbyb: Anodes
                        Qtpfbyc: Cathodes
                        Qtpfbye: Battery electrodes
                            Qtpfbyec: Charge collectors
                        Qtpfbyh: Battery separators
                Qtpff: Fuel cells
                Qtpfh: Hydraulic accumulators
                Qtpfs: Solar collectors
                    Qtpfss: Solar cells
            Qtph: Handling and conveying equipment
                Qtphc: Cargo handling equipment
                    Qtphch: Hand trucks
                        Qtphchd: Dollies
                    Qtphcm: Loaders
                    Qtphcu: Unloaders
                        Qtphcuc: Car dumpers
                Qtphd: Catapults
                Qtphe: Conveyors
                    Qtpheb: Belt conveyors
                    Qtphep: Pneumatic conveyors
                    Qtphes: People movers
                Qtphh: Hoses and nozzles
                    Qtphhh: Hoses
                        Qtphhhw: Water cannons
                    Qtphhn: Nozzles
                Qtphm: Lifting equipment
                    Qtphmb: Booms (Lifting equipment)
                    Qtphmc: Cranes
                        Qtphmcf: Floating cranes
                        Qtphmcm: Mobile cranes
                    Qtphmd: Derricks
                    Qtphmf: Fork lifts
                    Qtphmh: Hoists
                    Qtphmj: Jacks (Mechanical equipment)
                        Qtphmjh: Hydraulic jacks
                    Qtphmp: Pallets
                    Qtphms: Slings
                    Qtphmv: Winches
                    Qtphmw: Wheelchair lifts
            Qtpk: Containing equipment
                Qtpka: Bags
                Qtpkb: Boxes
                Qtpkc: Casks
                Qtpke: Containers
                Qtpkg: Drums (Containers)
                Qtpkk: Gabions
                Qtpkm: Hoppers
                Qtpkn: Pressure vessels
                Qtpkp: Process vessels
                    Qtpkpc: Coalescers
                Qtpkt: Tanks (Containers)
                    Qtpktb: Ballast tanks
                    Qtpkts: Septic tanks
            Qtpm: Heating, cooling and ventilation equipment
                Qtpmc: Cooling equipment
                    Qtpmcc: Air conditioners
                    Qtpmcr: Refrigerators
                Qtpmh: Heating equipment
                    Qtpmhb: Boilers
                        Qtpmhbc: Parts of boilers
                            Qtpmhbcb: Air preheaters
                            Qtpmhbcd: Boiler tubes
                                Qtpmhbcde: Economizers
                            Qtpmhbcf: Feedwater heaters
                    Qtpmhc: Burners
                        Qtpmhcp: Oil burners
                    Qtpmhd: Driers (Devices)
                    Qtpmhe: Evaporators
                    Qtpmhf: Furnaces
                        Qtpmhfb: Blast furnaces
                    Qtpmhh: Heat transfer devices
                        Qtpmhhe: Heat exchangers
                        Qtpmhhp: Heat pipes
                        Qtpmhhs: Heat sinks
                    Qtpmhk: Heaters
                        Qtpmhkw: Water heaters
                    Qtpmhm: Incinerators
                    Qtpmhp: Ovens
                        Qtpmhpb: Cement kilns
                        Qtpmhpd: Drying ovens
                Qtpmv: Ventilation equipment
                    Qtpmvb: Air intakes
                    Qtpmvc: Defoggers
                    Qtpmve: Defrosters
                    Qtpmvf: Fans
                    Qtpmvv: Ventilators
            Qtpn: Lighting equipment
                Qtpnm: Lamps
                    Qtpnme: Electric lamps
                        Qtpnmef: Fluorescent lamps
                            Qtpnmefv: Vacuum fluorescent lamps
                        Qtpnmej: Incandescent lamps
                        Qtpnmem: Mercury vapor lamps
                        Qtpnmes: Sodium vapor lamps
                    Qtpnmn: Lanterns
            Qtpo: Furniture
                Qtpoc: Consoles
                Qtpos: Seats
            Qtpr: Photographic equipment
                Qtprc: Cameras
                    Qtprcc: CCD cameras
                    Qtprcf: Digital cameras
                    Qtprcr: Stereoscopic cameras
                    Qtprct: Television cameras
                    Qtprcv: Video cameras
                Qtprf: Flash lamps
                Qtprv: Videotape recorders
            Qtps: Safety equipment
                Qtpsb: Barricades
                Qtpsc: Protective clothing
                    Qtpscb: Buckles (Fasteners)
                    Qtpscg: Goggles
                    Qtpsch: Safety hats
                        Qtpschh: Helmets
                            Qtpschhb: Bicycle helmets
                            Qtpschhm: Motorcycle helmets
                    Qtpscs: Sunglasses
                Qtpse: Emergency equipment
                    Qtpseb: Alarm systems
                    Qtpsed: Breathing apparatus
                    Qtpsef: Fire fighting equipment
                        Qtpseff: Fire extinguishers
                    Qtpseh: Flares
                    Qtpser: Rescue equipment
                        Qtpserm: Life preservers
                    Qtpsew: Warning devices
                Qtpsm: Medical equipment
                    Qtpsmf: First aid equipment
                    Qtpsmp: Oxygen equipment
                Qtpst: Training devices
                    Qtpsts: Training simulators
                        Qtpstsd: Driving simulators
                        Qtpstsf: Flight simulators
                        Qtpstsr: Railroad simulators
                        Qtpstss: Ship simulators
            Qtpt: Tools
                Qtptb: Augers
                Qtptc: Chisels
                    Qtptcg: Gouges
                Qtptd: Clamps
                Qtpte: Cutting tools
                    Qtptes: Shears (Tools)
                Qtptg: Drills
                    Qtptgd: Drill bits
                Qtptj: Grinders
                Qtptk: Hammers
                Qtptm: Machine tools
                    Qtptmm: Lathes
                    Qtptms: Sanders
                Qtptp: Planers
                Qtptr: Saws
                Qtptt: Screwdrivers
                Qtptv: Sprayers
                    Qtptvs: Spray guns
            Qtpu: Securing and joining equipment
                Qtpub: Anchors (Mooring devices)
                Qtpuc: Anchor windlasses
                Qtpud: Anchors (Structural connectors)
                Qtpuf: Arrester wires
                Qtpuh: Couplers
                Qtpuj: Drawbars
                Qtpuk: Flanges
                Qtpum: Gaskets
                Qtpur: Mooring cables
                Qtput: Rings (Devices)
                Qtpuv: Seals (Devices)
                    Qtpuvp: Oil seals
                Qtpuw: Tiedowns
                Qtpuy: Towing devices
                    Qtpuyh: Hitches
            Qtpv: Vending equipment
                Qtpvt: Ticket vending machines
            Qtpx: Data processing equipment
                Qtpxc: Calculators
                Qtpxm: Computers
                    Qtpxmb: Types of computers
                        Qtpxmbb: Analog computers
                            Qtpxmbbn: Network analyzers
                        Qtpxmbc: Digital computers
                        Qtpxmbe: Embedded systems
                        Qtpxmbg: Supercomputers
                        Qtpxmbj: Mainframe computers
                        Qtpxmbn: Minicomputers
                        Qtpxmbp: Microcomputers
                            Qtpxmbpc: Personal computers
                                Qtpxmbpch: Handheld computers
                                Qtpxmbpcm: Laptop computers
                        Qtpxmbr: Personal digital assistants
                        Qtpxmbs: Word processors
                        Qtpxmbv: Automotive computers
                    Qtpxmp: Computer components
                        Qtpxmpb: Central processing units (Computers)
                            Qtpxmpbb: Circuit boards (Computers)
                            Qtpxmpbc: Motherboards
                            Qtpxmpbd: Computer memory
                                Qtpxmpbdp: Random access memory
                                Qtpxmpbds: Read only memory
                            Qtpxmpbm: Logic circuits
                        Qtpxmpe: Computer chips
                            Qtpxmpem: Microprocessors
                        Qtpxmpg: Hard disks
                        Qtpxmpk: Keyboards
                        Qtpxmpp: Printers
                        Qtpxmpq: Video display terminals
                        Qtpxmpr: Visual display units (Computers)
                        Qtpxmps: Mice (Computers)
                        Qtpxmpv: Joysticks (Computers)
                        Qtpxmpx: Input output devices
                Qtpxp: Data plotters
                Qtpxr: Data recorders
                Qtpxs: Scanners
            Qtpy: Weapons
                Qtpyb: Bombs
                Qtpyg: Guns
                    Qtpygf: Firearms
                Qtpym: Weapons of mass destruction
                    Qtpymb: Biological and chemical weapons
                    Qtpymn: Nuclear weapons
                Qtpyo: Mines (Weapons)
        Qts: Assemblies (Equipment)
            Qtss: Subassemblies
                Qtssc: Components
                Qtssh: Housings
                Qtssp: Parts
                    Qtssps: Spare parts
    Qv: Equipment characteristics
        Qvd: Defects
        Qvf: Mechanical failure
            Qvfd: Degradation failures
            Qvfm: Leakage
                Qvfmb: Blowby
                Qvfms: Slippage (Leakage)
            Qvfv: Vapor lock
        Qvm: Mechanical loads
        Qvp: Performance
        Qvr: Reliability
        Qvs: Maintainability
        Qvt: Tolerances (Engineering)
R: Materials
    Rb: Classes of materials
        Rbb: States of matter
            Rbbb: Solids
            Rbbf: Fluids
                Rbbfb: Bubbles
                Rbbfh: Hydraulic fluids
                Rbbfj: Inviscid fluids
                Rbbfm: Liquids
                    Rbbfmm: Liquefied gases
                    Rbbfmp: Mist
                Rbbfs: Gases
                    Rbbfsj: Noble gases
                    Rbbfsv: Vapors
                        Rbbfsvc: Condensate
                        Rbbfsvd: Distillates
                Rbbfv: Viscous fluids
        Rbc: Chemicals
            Rbcb: Molecular structure
                Rbcbb: Atoms
                    Rbcbbs: Subatomic particles
                        Rbcbbsb: Atomic nucleus
                        Rbcbbse: Electrons
                        Rbcbbsn: Neutrons
                        Rbcbbsp: Protons
                Rbcbf: Ions
                    Rbcbfg: Anions
                    Rbcbfm: Cations
                Rbcbs: Isotopes
                    Rbcbsr: Radioisotopes
                Rbcbv: Molecules
                    Rbcbvm: Monomers
            Rbce: Chemical elements
                Rbceb: Classes of chemical elements
                    Rbcebb: Alkali metals
                    Rbcebh: Halogens
                    Rbcebn: Nonmetals
                    Rbcebr: Trace elements
                    Rbcebt: Transuranium elements
                Rbcef: Chemical elements by group and name
                    Rbcefb: Group I elements
                        Rbcefbd: Hydrogen
                            Rbcefbdd: Deuterium
                            Rbcefbdt: Tritium
                        Rbcefbm: Lithium
                        Rbcefbs: Sodium
                    Rbcefc: Group II elements
                        Rbcefcb: Barium
                        Rbcefcd: Beryllium
                        Rbcefcm: Calcium
                        Rbcefcq: Magnesium
                    Rbcefd: Transition elements
                        Rbcefdb: Cadmium
                        Rbcefdc: Chromium
                        Rbcefdd: Cobalt
                        Rbcefde: Copper
                        Rbcefdf: Gold
                        Rbcefdg: Iron
                        Rbcefdh: Manganese
                        Rbcefdj: Mercury
                        Rbcefdk: Molybdenum
                        Rbcefdm: Nickel
                        Rbcefdn: Palladium
                        Rbcefdo: Platinum
                        Rbcefdp: Potassium
                        Rbcefdq: Silver
                        Rbcefdr: Titanium
                        Rbcefds: Tungsten
                        Rbcefdu: Vanadium
                        Rbcefdv: Zinc
                        Rbcefdw: Zirconium
                    Rbcefe: Group III elements
                        Rbcefem: Aluminum
                        Rbcefer: Boron
                    Rbceff: Group IV elements
                        Rbceffc: Carbon
                        Rbceffm: Lead (Metal)
                        Rbceffs: Silicon
                        Rbcefft: Tin
                    Rbcefg: Group V elements
                        Rbcefgn: Nitrogen
                            Rbcefgnc: Liquid nitrogen
                        Rbcefgp: Phosphorus
                    Rbcefh: Group VI elements
                        Rbcefhm: Oxygen
                            Rbcefhmn: Ozone
                        Rbcefhr: Selenium
                        Rbcefhs: Sulfur
                    Rbcefj: Group VII elements
                        Rbcefjb: Bromine
                        Rbcefjc: Chlorine
                        Rbcefjf: Fluorine
                        Rbcefjj: Iodine
                    Rbcefk: Group 0 elements
                        Rbcefkh: Helium
                        Rbcefkr: Radon
                        Rbcefkx: Xenon
                    Rbcefm: Actinides
                        Rbcefmp: Plutonium
                        Rbcefmu: Uranium
            Rbcg: Chemical compounds
                Rbcgc: Chemical compounds by primary element or compound
                    Rbcgcb: Alkali metal compounds
                    Rbcgcc: Aluminum compounds
                    Rbcgcd: Ammonium compounds
                    Rbcgce: Calcium compounds
                    Rbcgcf: Carbonates
                    Rbcgcg: Chlorine compounds
                        Rbcgcgd: Chlorides
                    Rbcgch: Halides
                    Rbcgcj: Hydrates
                    Rbcgck: Hydroxides
                    Rbcgcm: Iron compounds
                    Rbcgcn: Lead compounds
                    Rbcgcp: Lithium compounds
                    Rbcgcq: Magnesium compounds
                    Rbcgcr: Nitrogen compounds
                        Rbcgcrc: Nitrates
                        Rbcgcrf: Nitrites
                    Rbcgcs: Oxides
                    Rbcgct: Phosphates
                    Rbcgcu: Silicon compounds
                    Rbcgcv: Sodium compounds
                    Rbcgcw: Sulfur compounds
                        Rbcgcwc: Polysulfides
                        Rbcgcwf: Sulfates
                        Rbcgcwh: Sulfides
                        Rbcgcwk: Sulfites
                        Rbcgcwn: Sulfonates
                Rbcgn: Inorganic compounds
                    Rbcgnb: Aluminum inorganic compounds
                        Rbcgnbd: Alumina
                        Rbcgnbm: Aluminates
                        Rbcgnbr: Aluminum oxide
                    Rbcgnc: Ammonia
                    Rbcgne: Calcium inorganic compounds
                        Rbcgneb: Calcium carbonate
                        Rbcgned: Calcium chloride
                        Rbcgneg: Calcium hydroxide
                        Rbcgnej: Calcium nitrite
                        Rbcgnem: Calcium oxide
                        Rbcgnep: Calcium silicate
                            Rbcgnepp: Tricalcium silicate
                            Rbcgnept: Tobermorite
                        Rbcgner: Calcium sulfates
                        Rbcgnet: Tricalcium aluminate
                    Rbcgnf: Carbon inorganic compounds
                        Rbcgnff: Carbides
                        Rbcgnfm: Carbon dioxide
                        Rbcgnfq: Carbon monoxide
                    Rbcgng: Chlorites
                    Rbcgnh: Cyanides
                    Rbcgnj: Fluorides
                    Rbcgnk: Hydrogen inorganic compounds
                        Rbcgnkb: Hydrazine
                        Rbcgnkf: Hydrides
                        Rbcgnkh: Hydrochloric acid
                        Rbcgnkp: Hydrogen peroxide
                        Rbcgnkt: Hydrogen sulfide
                    Rbcgnm: Iron inorganic compounds
                        Rbcgnmf: Ferrites
                        Rbcgnmp: Ferrous sulfide
                        Rbcgnmt: Iron oxides
                    Rbcgnp: Lithium chloride
                    Rbcgnq: Magnesium chloride
                    Rbcgnr: Nitrogen inorganic compounds
                        Rbcgnrd: Inorganic nitrates
                        Rbcgnrm: Nitric acid
                        Rbcgnrr: Nitric oxide
                        Rbcgnru: Nitrogen oxides
                            Rbcgnrun: Nitrogen dioxide
                    Rbcgns: Phosphorus inorganic compounds
                        Rbcgnsk: Inorganic phosphates
                        Rbcgnsp: Phosphoric acid
                    Rbcgnt: Potassium chloride
                    Rbcgnu: Silicon inorganic compounds
                        Rbcgnuc: Silane
                        Rbcgnuf: Silica gel
                        Rbcgnuh: Silicates
                        Rbcgnum: Silicon carbide
                        Rbcgnup: Silicon dioxide
                        Rbcgnut: Silicon nitride
                    Rbcgnv: Sodium inorganic compounds
                        Rbcgnvc: Sodium carbonate
                        Rbcgnvg: Sodium chloride
                        Rbcgnvk: Sodium hydroxide
                        Rbcgnvp: Sodium silicate
                        Rbcgnvs: Sodium sulfate
                    Rbcgny: Sulfur inorganic compounds
                        Rbcgnym: Sulfur oxides
                            Rbcgnymm: Sulfur dioxide
                        Rbcgnyt: Sulfuric acid
                    Rbcgnz: Uranium inorganic compounds
                        Rbcgnzm: Uranyl acetate
                Rbcgr: Organic compounds
                    Rbcgrb: Groups of organic compounds
                        Rbcgrbb: Acetates
                        Rbcgrbc: Alcohols
                            Rbcgrbcd: Carbinols
                        Rbcgrbd: Aldehydes
                        Rbcgrbe: Aliphatic compounds
                        Rbcgrbf: Amides
                        Rbcgrbg: Amines
                        Rbcgrbh: Aromatic compounds
                            Rbcgrbhp: Polar aromatic compounds
                        Rbcgrbj: Carbohydrates
                        Rbcgrbk: Chlorine organic compounds
                        Rbcgrbm: Epoxides
                        Rbcgrbn: Esters
                        Rbcgrbp: Ethers
                        Rbcgrbq: Ethylenes
                        Rbcgrbr: Glycols
                        Rbcgrbs: Halogenated compounds
                        Rbcgrbt: Hydrocarbons
                            Rbcgrbtb: Aromatic hydrocarbons
                            Rbcgrbtm: Olefins
                            Rbcgrbts: Polyvinyl hydrocarbons
                        Rbcgrbu: Ketones
                        Rbcgrbv: Organometallic compounds
                        Rbcgrbw: Polycarbonates
                        Rbcgrby: Styrenes
                    Rbcgrr: Individual organic compounds
                        Rbcgrrb: Acetic acid
                        Rbcgrrc: Benzene
                        Rbcgrrd: Butadiene
                            Rbcgrrds: Styrene butadiene styrene
                        Rbcgrre: Butane
                        Rbcgrrf: Calcium magnesium acetate
                        Rbcgrrg: Carbene
                        Rbcgrrh: Ethanol
                        Rbcgrrj: Ethylene glycol
                        Rbcgrrk: Formaldehyde
                        Rbcgrrl: Methane
                        Rbcgrrm: Methanol
                        Rbcgrrn: Methyl methacrylate
                        Rbcgrro: Phenol
                        Rbcgrrp: Polymethyl methacrylate
                        Rbcgrrq: Polypropylene
                        Rbcgrrr: Polystyrene
                        Rbcgrrs: Polytetrafluoroethylene
                        Rbcgrrt: Polyvinyl acetate
                        Rbcgrru: Polyvinyl chloride
                        Rbcgrrv: Tetraethyl lead
                        Rbcgrrw: Toluene
                        Rbcgrrx: Urea
                        Rbcgrry: Urethane
                Rbcgs: Salts
                    Rbcgsn: Inorganic salts
                    Rbcgsr: Organic salts
                    Rbcgss: Soluble salts
            Rbct: Chemical substances
                Rbcta: Accelerators (Materials)
                Rbctb: Anodic materials
                    Rbctbs: Sacrificial anodes
                Rbctd: Catalysts
                    Rbctdm: Monolithic catalysts
                    Rbctdp: Oxidation catalysts
                    Rbctds: Pelleted catalysts
                Rbctf: Extenders
                Rbctg: Flocculating agents
                Rbcth: Flotation agents
                Rbctk: Inhibitors (Chemistry)
                    Rbctkb: Antioxidants
                    Rbctkr: Retarders (Chemistry)
                        Rbctkrc: Retarders (Concrete)
                Rbctm: Mixtures
                    Rbctma: Additives
                    Rbctmb: Blends
                    Rbctmc: Colloidal systems
                        Rbctmcc: Colloids
                        Rbctmcg: Gels
                    Rbctmd: Dispersions (Chemistry)
                        Rbctmdd: Dispersers
                        Rbctmde: Emulsions
                        Rbctmdq: Smoke
                        Rbctmds: Sprays (Materials)
                    Rbctmf: Formulations
                    Rbctmq: Solutions (Chemistry)
                        Rbctmqd: Dissolved gases
                        Rbctmqe: Electrolytes
                        Rbctmqm: Leachate
                        Rbctmqr: Solvents
                            Rbctmqrb: Organic solvents
                    Rbctms: Suspensions (Chemistry)
                        Rbctmsb: Aerosols
                        Rbctmsf: Free water
                        Rbctmss: Slurry
                            Rbctmssb: Bentonite slurry
                Rbctp: Oxidizing agents
                    Rbctpp: Photochemical oxidants
                Rbctr: Chemical substances by pH
                    Rbctrb: Acids
                    Rbctrg: Bases (Chemistry)
                        Rbctrgb: Alkali
                Rbcts: Polymers
                    Rbctsf: Copolymers
                Rbctt: Reagents
                Rbctv: Tracers (Chemistry)
                Rbcty: Wetting agents
        Rbd: Water
            Rbdb: Water phases
                Rbdbf: Ice
                Rbdbk: Slush
                Rbdbn: Snow
                Rbdbt: Water vapor
            Rbdm: Water by salt content
                Rbdmf: Fresh water
                    Rbdmfd: Drinking water
                Rbdms: Seawater
        Rbe: Natural earth crust materials
            Rbeb: Deposits (Geology)
                Rbebb: Alluvium
                Rbebf: Colluvium
                Rbebk: Lacustrine deposits
                Rbebl: Lenses (Geology)
                Rbebm: Marine deposits
                Rbebn: Mineral deposits
                Rbebo: Organic deposits
                Rbebp: Talus
                Rbebq: Till
                Rbebr: Moraines
                Rbebs: Sediments
                Rbebv: Volcanic deposits
            Rbed: Weathered earth crust materials
                Rbedn: Laterites
            Rbep: Parent materials
            Rber: Rocks
                Rberb: Lithologic composition
                    Rberbc: Rock core
                    Rberbp: Pores (Geology)
                        Rberbps: Pore space
                Rberg: Igneous rocks
                    Rbergb: Alkalic rock
                    Rbergc: Basalt
                    Rbergd: Dolerite
                    Rbergg: Gabbro
                    Rbergn: Granite
                    Rbergp: Porphyry
                    Rbergt: Trap rock
                    Rbergv: Volcanic rock
                        Rbergvp: Pumice
                Rberh: Sedimentary rocks
                    Rberhb: Arenites
                    Rberhc: Calcretes
                    Rberhd: Chalks
                    Rberhf: Cherts
                    Rberhg: Clastic rocks
                    Rberhh: Conglomerates (Geology)
                    Rberhj: Dolomite
                    Rberhm: Limestone
                    Rberhp: Mudstones
                    Rberhr: Oil shales
                    Rberht: Sandstones
                    Rberhu: Shale
                    Rberhv: Silica stone
                    Rberhy: Siltstones
                Rberm: Metamorphic rocks
                    Rbermg: Gneiss
                    Rbermj: Illites
                    Rbermm: Marble
                    Rbermq: Quartzite
                    Rberms: Schist
                    Rbermt: Slate
                Rberp: Ores
                    Rberpb: Bauxite
                    Rberpr: Iron ores
                Rberr: Minerals
                    Rberra: Amber
                    Rberrb: Asbestos
                    Rberrc: Calcites
                    Rberrd: Carbonate rocks
                    Rberre: Chromates
                    Rberrf: Clay minerals
                        Rberrfb: Bentonite
                        Rberrfh: Halloysite
                        Rberrfk: Kaolin
                            Rberrfkk: Kaolinite
                        Rberrfm: Montmorillonite
                        Rberrfv: Vermiculite
                    Rberrg: Diamonds
                    Rberrh: Ettringite
                    Rberrj: Feldspar
                    Rberrk: Flint
                    Rberrm: Graphite
                    Rberrn: Gypsum
                    Rberrp: Halite
                    Rberrq: Mica
                    Rberrr: Phosphate rock
                    Rberrs: Pyrite
                    Rberrt: Quartz
                        Rberrtr: Rock crystals
                            Rberrtrp: Prisms
                    Rberrv: Silica
                        Rberrvp: Opals
                Rbers: Coal
                    Rbersb: Anthracite
                    Rbersd: Bituminous coal
                    Rbersm: Lignite
                    Rberss: Subbituminous coal
                Rbert: Rocks by properties
                    Rbertb: Bedrock
                    Rbertc: Boulders
                    Rbertd: Breccia
                    Rbertf: Crystalline rocks
                    Rberth: Decomposed rock
                        Rberthi: Drift
                    Rbertj: Fractured rock
                    Rbertm: Manganese nodules
                    Rbertp: Organic rocks
                    Rbertq: Overburdens
                    Rbertr: Soft rock
                    Rberts: Strata
                    Rbertt: Weak rock
                    Rbertw: Weathered rock
            Rbes: Soils
                Rbesb: Soil components
                    Rbesbb: Soil air
                    Rbesbp: Soil particles
                    Rbesbw: Groundwater
                        Rbesbwc: Capillary water
                        Rbesbwp: Phreatic water
                        Rbesbws: Soil water
                        Rbesbwv: Vadose water
                Rbesc: Soil series
                Rbesf: Soil groups
                    Rbesfc: Cohesive soils
                    Rbesfg: Granular soils
                Rbesg: Soil types
                    Rbesgc: Clay soils
                        Rbesgcb: Clay water systems
                        Rbesgce: Expansive clays
                        Rbesgcj: Marine clays
                        Rbesgck: Marl
                        Rbesgcm: Pozzolan
                        Rbesgcn: Sandy clays
                        Rbesgcp: Sensitive clays
                        Rbesgcr: Silty clays
                        Rbesgct: Soft clays
                        Rbesgcv: Varved clays
                    Rbesgd: Cobbles
                    Rbesgg: Gravel
                        Rbesggg: Gravelly soils
                        Rbesggk: Lateritic gravels
                        Rbesggs: Sandy gravels
                    Rbesgs: Sand
                        Rbesgsb: Asphaltic sand
                        Rbesgsd: Beach sands
                        Rbesgsf: Bituminous sands
                        Rbesgsh: Dune sands
                        Rbesgsp: Sand deposits
                        Rbesgsq: Sandy soils
                        Rbesgsr: Silica sands
                        Rbesgss: Silty sands
                        Rbesgst: Tar sands
                    Rbesgt: Silts
                        Rbesgtk: Loess
                        Rbesgtm: Silty loams
                Rbesj: Soil deposits
                    Rbesjr: Residual soils
                    Rbesjs: Suspended sediments
                    Rbesjv: Volcanic ash
                Rbesm: Soils by place
                    Rbesmg: Glacial soils
                    Rbesmk: Lacustrine soils
                    Rbesmm: Marine soils
                    Rbesmp: Ocean bottom soils
                Rbesp: Soils by properties
                    Rbespb: Soils by chemical content or action
                        Rbespbb: Acid soils
                        Rbespbc: Calcareous soils
                            Rbespbcb: Black cotton soils
                        Rbespbd: Corrosive soils
                        Rbespbj: Lateritic soils
                        Rbespbk: Limestone soils
                        Rbespbm: Micaceous soils
                        Rbespbs: Saline soils
                    Rbespc: Soils by consistency
                        Rbespcp: Plastic soils
                        Rbespcs: Soft soils
                    Rbespd: Soils by density
                        Rbespdd: Dense soils
                        Rbespdm: Loose soils
                    Rbespf: Soils by frost condition or potential
                        Rbespfd: Frost heaving soils
                        Rbespff: Frost susceptible soil
                        Rbespfh: Frozen soils
                            Rbespfhs: Seasonally frozen ground
                        Rbespfp: Permafrost
                    Rbespg: Soils by grain size and distribution
                        Rbespgc: Coarse grained soils
                        Rbespgf: Fine grained soils
                        Rbespgh: Homogeneous soils
                    Rbesph: Soil horizon
                        Rbesphs: Subsoil
                        Rbespht: Topsoil
                            Rbesphtt: Turf
                        Rbesphy: Soil profiles
                    Rbespm: Soils by moisture content or potential
                        Rbespmb: Air dried soil
                        Rbespmm: Mud
                        Rbespms: Saturated soils
                        Rbespmt: Sludge (Deposit)
                        Rbespmv: Swelling soils
                        Rbespmy: Unsaturated soils
                        Rbespmz: Vertisols
                    Rbespn: Soils by organic content
                        Rbespnh: Humus
                        Rbespnm: Loam
                        Rbespnn: Organic soils
                        Rbespnp: Peat
                        Rbespnq: Peat soils
                    Rbespp: Soils by permeability
                        Rbesppk: Impervious soils
                        Rbesppp: Pervious soils
                    Rbesps: Soils by strength
                        Rbespsc: Collapsible soils
                        Rbespsf: Compressible soils
                        Rbespsu: Unstable soil
                    Rbespt: Soil structure
                        Rbesptm: Layered soils
                        Rbesptu: Unconsolidated soils
            Rbeu: Petroleum
                Rbeug: Petroleum gases
                    Rbeugn: Natural gas
                Rbeum: Petroleum liquids
                    Rbeumc: Crude oil
                    Rbeumm: Maltha
                Rbeus: Petroleum solids
                    Rbeusb: Asphalt
                        Rbeusbf: Asphalt rock
                        Rbeusbt: Trinidad asphalt
                    Rbeush: Bitumen
                    Rbeusp: Tar
        Rbf: Fuels
            Rbfc: Fuel composition
                Rbfcb: Fuel additives
                    Rbfcbb: Antiknock compounds
                        Rbfcbbt: Tetraethyl lead
                    Rbfcbp: Oxidizers
                Rbfce: Fuel emulsions
                Rbfcm: Fuel mixtures
            Rbfd: Alcohol fuels
                Rbfdm: Methanol fuels
            Rbfe: Biomass fuels
            Rbff: Fossil fuels
                Rbffe: Coal fuels
                    Rbffed: Coal gas
                Rbffp: Petroleum fuels
                    Rbffpk: Kerosene
                    Rbffpn: Natural gas
                        Rbffpnc: Compressed natural gas
                        Rbffpnm: Liquefied natural gas
                    Rbffpp: Liquefied petroleum gas
            Rbfh: Hydrogen fuels
                Rbfhm: Liquid hydrogen
            Rbfn: Nuclear fuels
                Rbfns: Spent reactor fuels
            Rbfp: Fuels by properties
                Rbfpb: Alternate fuels
                Rbfpc: Clean fuels
                Rbfpd: Fuel air mixtures
                Rbfpe: Fuel gas
                Rbfpg: Fuel oils
                Rbfpj: Lean fuel mixtures
                Rbfpm: Liquid fuels
                Rbfpr: Residual fuels
                Rbfps: Synthetic fuels
                Rbfpu: Unburned fuels
            Rbfu: Fuels by end use
                Rbfub: Aviation fuels
                    Rbfubb: Aircraft fuels
                        Rbfubbj: Jet engine fuels
                Rbfug: Gas turbine fuels
                Rbfum: Motor fuels
                    Rbfumd: Diesel fuels
                        Rbfumdb: Biodiesel fuels
                    Rbfumg: Gasoline
                        Rbfumgg: Gasohol
                        Rbfumgm: Leaded gasoline
                        Rbfumgu: Unleaded gasoline
                        Rbfumgx: Reformulated gasoline
                Rbfus: Spacecraft fuels
                    Rbfusp: Propellants
        Rbj: Air
            Rbjc: Compressed air
        Rbm: Building materials
            Rbmd: Building materials by properties
                Rbmdb: Engineering soils
                    Rbmdbb: Backfill soils
                    Rbmdbc: Cement treated soils
                        Rbmdbcs: Soil cement
                    Rbmdbe: Compacted soils
                        Rbmdbec: Compacted clays
                    Rbmdbf: Drained soil
                    Rbmdbh: Foundation soils
                    Rbmdbi: Membrane encapsulated soil layers
                    Rbmdbj: Reinforced earth
                    Rbmdbm: Remolded soils
                        Rbmdbmc: Remolded clay soils
                    Rbmdbs: Soil lime mixtures
                Rbmdd: Aggregates, rock and stone
                    Rbmddc: Aggregates
                        Rbmddcc: Aggregates by source
                            Rbmddccb: Artificial aggregates
                                Rbmddccbe: Expanded clay aggregates
                                Rbmddccbg: Expanded shale aggregates
                                Rbmddccbm: Lightweight aggregates
                                Rbmddccbs: Slag coarse aggregates
                            Rbmddccn: Natural aggregates
                                Rbmddccnb: Basalt coarse aggregates
                                Rbmddccnm: Limestone aggregates
                                Rbmddccnn: Mineral aggregates
                                Rbmddccnv: Volcanic aggregates
                        Rbmddcf: Aggregates by gradation
                            Rbmddcfc: Continuously graded aggregates
                            Rbmddcfd: Dense graded aggregates
                            Rbmddcfg: Gap graded aggregates
                            Rbmddcfp: Open graded aggregates
                        Rbmddcj: Aggregates by shape and surface texture
                            Rbmddcjc: Coarse aggregates
                            Rbmddcjf: Fine aggregates
                            Rbmddcjj: Interlocking aggregates
                            Rbmddcjr: Rounded aggregates
                        Rbmddcm: Aggregates by relationship to concrete
                            Rbmddcmd: Deleterious materials
                            Rbmddcmr: Reactive aggregates
                        Rbmddcp: Aggregates by treatment
                            Rbmddcpc: Calcined aggregates
                            Rbmddcpf: Crushed aggregates
                            Rbmddcpj: Crusher run aggregates
                            Rbmddcpp: Precoated aggregates
                        Rbmddcs: Aggregate mixtures
                            Rbmddcsb: Bituminous aggregates
                            Rbmddcsc: Concrete aggregates
                            Rbmddcss: Soil aggregates
                    Rbmddr: Rock in building
                        Rbmddrc: Chippings
                            Rbmddrcc: Coated chippings
                        Rbmddrj: Crushed rock
                            Rbmddrjm: Crushed limestone
                    Rbmddt: Stone
                        Rbmddtp: Paving stones
                    Rbmddv: Consolidated aggregates, rock and stone
                        Rbmddvb: Ballast (Railroads)
                            Rbmddvbb: Asphalt ballast
                            Rbmddvbs: Subballast
                        Rbmddvm: Macadam
                            Rbmddvmb: Bituminous macadam
                            Rbmddvmp: Penetration macadam
                            Rbmddvmw: Water bound macadam
                Rbmdf: Ceramic materials
                    Rbmdfb: Brick
                    Rbmdfc: Cement
                        Rbmdfcb: Air entraining cement
                        Rbmdfcd: Aluminous cement
                        Rbmdfcf: Asbestos cement
                        Rbmdfch: Expansive cement
                        Rbmdfcj: Gypsum cement
                        Rbmdfcm: High early strength cement
                        Rbmdfcp: Hydraulic cement
                        Rbmdfcr: Lime cement
                        Rbmdfct: Portland cement
                            Rbmdfctp: Portland pozzolan cement
                        Rbmdfcu: Slag cement
                        Rbmdfcx: Sulfate resisting cement
                        Rbmdfcy: Cement additives
                            Rbmdfcyt: Tobermorite
                    Rbmdfe: Cermets
                    Rbmdfk: Clay
                        Rbmdfke: Expanded clay
                        Rbmdfkv: Vitrified clay
                    Rbmdfm: Glass
                        Rbmdfmb: Glass beads
                        Rbmdfms: Safety glass
                            Rbmdfmsn: Nonshattering glass
                            Rbmdfmst: Tempered glass
                        Rbmdfmu: Tinted glass
                        Rbmdfmw: Window glass
                    Rbmdfp: Plaster
                    Rbmdfs: Stucco
                Rbmdh: Composite materials
                    Rbmdhb: Types of composites
                        Rbmdhbf: Fiber composites
                            Rbmdhbfg: Fiberglass
                        Rbmdhbp: Concrete plastic composites
                    Rbmdhc: Concrete
                        Rbmdhcb: Types of concrete
                            Rbmdhcbb: Air entrained concrete
                            Rbmdhcbc: Cast in place concrete
                            Rbmdhcbd: Cellular concrete
                            Rbmdhcbe: Expansive concrete
                            Rbmdhcbf: Fresh concrete
                            Rbmdhcbg: High performance concrete
                                Rbmdhcbgs: High strength concrete
                            Rbmdhcbh: Lean concrete
                                Rbmdhcbhe: Econocrete
                            Rbmdhcbj: Lightweight concrete
                            Rbmdhcbk: Mass concrete
                            Rbmdhcbm: Microconcrete
                            Rbmdhcbn: Porous concrete
                            Rbmdhcbo: Portland cement concrete
                            Rbmdhcbp: Precast concrete
                            Rbmdhcbq: Prestressed concrete
                            Rbmdhcbr: Pumped concrete
                                Rbmdhcbrs: Shotcrete
                            Rbmdhcbs: Ready mixed concrete
                            Rbmdhcbt: Reinforced concrete
                                Rbmdhcbtc: Confined concrete
                                Rbmdhcbtt: Tied concrete
                            Rbmdhcbu: Roller compacted concrete
                            Rbmdhcbv: Self compacting concrete
                            Rbmdhcbw: Tremie concrete
                            Rbmdhcbx: Unreinforced concrete
                        Rbmdhcj: Curing and setting agents
                            Rbmdhcjc: Air entraining agents
                            Rbmdhcjf: Accelerating agents
                            Rbmdhcjj: Curing agents
                            Rbmdhcjr: Retarders (Concrete)
                            Rbmdhcjw: Water reducing agents
                        Rbmdhcm: Admixtures
                            Rbmdhcmg: Fiber reinforced concrete
                                Rbmdhcmgf: Glass fiber reinforced concrete
                            Rbmdhcmp: Polymer concrete
                                Rbmdhcmpk: Latex modified concrete
                        Rbmdhcu: Air voids
                            Rbmdhcuf: Entrained air
                            Rbmdhcur: Entrapped air
                        Rbmdhcw: Water in concrete
                            Rbmdhcwm: Concrete mixing water
                            Rbmdhcwp: Pore water
                    Rbmdhf: Ferrocement
                Rbmdk: Metals
                    Rbmdkb: Types of metals
                        Rbmdkbb: Base metal
                            Rbmdkbbh: Heat affected zone (Metals)
                        Rbmdkbc: Cast iron
                        Rbmdkbd: Clad metals
                        Rbmdkbe: Corrugated metals
                            Rbmdkbeb: Corrugated aluminum
                            Rbmdkbes: Corrugated steel
                        Rbmdkbf: Die castings
                        Rbmdkbg: Galvanized metals
                        Rbmdkbh: Heavy metals
                        Rbmdkbm: Light metals
                        Rbmdkbt: Steel castings
                        Rbmdkbw: Weld metal
                    Rbmdkd: Alloys
                        Rbmdkdb: Aluminum alloys
                        Rbmdkdc: Copper alloys
                            Rbmdkdcb: Brass
                        Rbmdkdf: Iron alloys
                            Rbmdkdfb: Austenite
                            Rbmdkdfs: Steel
                                Rbmdkdfsc: Steel by properties
                                    Rbmdkdfscb: Alloy steel
                                    Rbmdkdfscc: Carbon steel
                                        Rbmdkdfsccm: Low alloy steel
                                            Rbmdkdfsccmh: HY 80 steel
                                        Rbmdkdfsccp: Mild steel
                                    Rbmdkdfscd: Cast steel
                                    Rbmdkdfscf: Corrosion resistant steel
                                        Rbmdkdfscfs: Stainless steel
                                    Rbmdkdfscm: High strength steel
                                        Rbmdkdfscmd: Dual phase steel
                                    Rbmdkdfscw: Weathering steel
                                Rbmdkdfse: Steel by end use
                                    Rbmdkdfsef: Rail steel
                                    Rbmdkdfseh: Reinforcing steel
                                    Rbmdkdfsep: Shipbuilding steel
                                    Rbmdkdfses: Structural steel
                        Rbmdkdk: Lithium alloys
                        Rbmdkdm: Magnesium alloys
                        Rbmdkdn: Nickel alloys
                        Rbmdkds: Silicon alloys
                        Rbmdkdt: Titanium alloys
                        Rbmdkdu: Zinc alloys
                        Rbmdkdy: Alloys by properties
                            Rbmdkdyc: Corrosion resistant alloys
                            Rbmdkdyw: Wear resistant alloys
                Rbmdm: Organic materials
                    Rbmdmb: Animal materials
                        Rbmdmbc: Coral
                        Rbmdmbm: Leather
                        Rbmdmbs: Shells (Zoology)
                    Rbmdmv: Vegetable materials
                        Rbmdmvc: Bamboo
                        Rbmdmve: Burlap
                        Rbmdmvf: Compost
                        Rbmdmvg: Lignin
                        Rbmdmvj: Lignosulfonate
                        Rbmdmvm: Mulches
                        Rbmdmvs: Straw
                        Rbmdmvw: Wood
                            Rbmdmvwb: Bark
                            Rbmdmvwd: Cellulose
                            Rbmdmvwf: Hardwoods
                            Rbmdmvwj: Laminated wood
                            Rbmdmvwm: Logs
                            Rbmdmvwp: Lumber
                            Rbmdmvwr: Plywood
                            Rbmdmvws: Soft woods
                            Rbmdmvwt: Timber
                            Rbmdmvww: Wood chips
                Rbmdp: Hydrocarbon based materials
                    Rbmdpb: Asphalt based materials
                        Rbmdpbb: Asphalt cement
                        Rbmdpbe: Emulsified asphalt
                            Rbmdpbeb: Anionic emulsified asphalt
                            Rbmdpbec: Cationic emulsified asphalt
                        Rbmdpbg: Gussasphalt
                        Rbmdpbh: Foamed asphalt
                        Rbmdpbm: Liquid asphalt
                        Rbmdpbr: Rolled asphalt
                        Rbmdpbs: Sheet asphalt
                        Rbmdpbu: Asphalt mixtures
                            Rbmdpbub: Asphalt concrete
                                Rbmdpbubp: Plant mix
                            Rbmdpbum: Mastic asphalt
                            Rbmdpbuq: Stone matrix asphalt
                            Rbmdpbus: Superpave
                        Rbmdpby: Asphalt additives
                            Rbmdpbyp: Polymer asphalt
                                Rbmdpbype: Elastomer modified asphalt
                                    Rbmdpbypem: Latex asphalt
                                    Rbmdpbyper: Asphalt rubber
                            Rbmdpbys: Sulfur asphalt
                    Rbmdpc: Bituminous materials
                        Rbmdpcm: Bituminous mixtures
                        Rbmdpcr: Rubberized bitumen
                    Rbmdpf: Coal based materials
                        Rbmdpfc: Coal liquids
                        Rbmdpff: Coal tars
                        Rbmdpfm: Coke
                        Rbmdpfp: Creosote
                    Rbmdpm: Maltha based materials
                        Rbmdpmm: Malthene
                    Rbmdpp: Petrochemicals
                        Rbmdppb: Asphaltene
                        Rbmdppd: Petroleum distillates
                        Rbmdppf: Naphtha
                        Rbmdppp: Paraffin
                            Rbmdpppq: Propane
                        Rbmdpps: Residual oils
                    Rbmdpt: Hydrocarbon based materials from multiple sources
                        Rbmdptc: Carbon black
                        Rbmdptp: Pitch (Materials)
                        Rbmdpts: Synthetic crude
                        Rbmdptv: Synthetic crude oil
                Rbmdq: Plastics
                    Rbmdqb: Formed plastics
                        Rbmdqbc: Corrugated plastic
                        Rbmdqbe: Expanded plastics
                        Rbmdqbm: Laminated plastics
                    Rbmdqd: Elastomers
                        Rbmdqdm: Latex
                        Rbmdqdr: Rubber
                            Rbmdqdrc: Rubber compounds
                                Rbmdqdrcb: Asphalt rubber
                                Rbmdqdrcc: Chlorinated rubber
                                Rbmdqdrcs: Styrene butadiene rubber
                            Rbmdqdrk: Natural rubber
                            Rbmdqdrn: Neoprene
                            Rbmdqdrr: Reclaimed rubber
                            Rbmdqdrs: Synthetic rubber
                    Rbmdqn: Nylon
                    Rbmdqp: Phenolic plastic
                    Rbmdqq: Reinforced plastics
                        Rbmdqqf: Fiber reinforced plastics
                            Rbmdqqfg: Glass fiber reinforced plastics
                    Rbmdqr: Resins
                        Rbmdqrb: Acrylic resins
                        Rbmdqrd: Alkyd resins
                        Rbmdqrf: Epoxy resins
                        Rbmdqrh: Ethylene resins
                        Rbmdqrj: Natural resins
                        Rbmdqrm: Phenolic resins
                        Rbmdqrn: Polyamide resins
                        Rbmdqrp: Polyester resins
                        Rbmdqrq: Polyurethane resins
                        Rbmdqrr: Synthetic resins
                        Rbmdqrs: Thermoplastic resins
                        Rbmdqru: Thermosetting resins
                        Rbmdqrv: Vinyl resins
                    Rbmdqs: Silicones
                    Rbmdqt: Thermoplastic materials
                    Rbmdqu: Thermosetting materials
                Rbmds: Hazardous materials
                    Rbmdsb: Carcinogens
                    Rbmdsc: Hazardous chemicals
                        Rbmdscc: Chemical agents
                        Rbmdscm: Corrosive materials
                    Rbmdse: Explosives
                        Rbmdsep: Plastic explosives
                    Rbmdsf: Flammable materials
                        Rbmdsfm: Flammable liquids
                    Rbmdsp: Poisons
                        Rbmdspg: Poisonous gases
                    Rbmdsr: Radioactive materials
                        Rbmdsrf: Fallout
                Rbmdu: Waste products
                    Rbmdua: Bottom ash
                    Rbmdub: Clinkers
                    Rbmduc: Crumb rubber
                    Rbmdud: Dredged materials
                    Rbmdue: Combustion deposits
                    Rbmduf: Dust
                        Rbmdufk: Kiln dust
                        Rbmdufm: Limestone dust
                        Rbmdufs: Sawdust
                    Rbmduh: Fly ash
                        Rbmduhm: Lime fly ash
                        Rbmduhp: Pulverized fly ash
                    Rbmduj: Foundry sand
                    Rbmdum: Recycled materials
                    Rbmdup: Rubble
                    Rbmdur: Scrap
                        Rbmdurs: Scrap metal
                    Rbmdut: Silica fume
                    Rbmduv: Slag
                        Rbmduvg: Granulated slag
                        Rbmduvp: Pelletized slag
                    Rbmduw: Tailings
                    Rbmduy: Wood waste
                Rbmdx: Materials by shape or form
                    Rbmdxa: Bars (Building materials)
                        Rbmdxam: Tendons (Materials)
                        Rbmdxar: Reinforcing bars
                            Rbmdxard: Deformed bars
                            Rbmdxars: Stirrups
                        Rbmdxas: Rods
                        Rbmdxat: Tie bars
                    Rbmdxb: Blocks
                        Rbmdxbc: Concrete blocks
                            Rbmdxbcm: Monoliths
                    Rbmdxc: Fabrics
                        Rbmdxcb: Ballast mats
                        Rbmdxcc: Filters
                            Rbmdxccf: Filter fabric
                        Rbmdxce: Geosynthetics
                            Rbmdxceg: Geogrids
                            Rbmdxcem: Geomembranes
                            Rbmdxcet: Geotextiles
                        Rbmdxch: Impervious membranes
                        Rbmdxcn: Nonwoven materials
                            Rbmdxcnt: Nonwoven textiles
                        Rbmdxcp: Rayon
                        Rbmdxcq: Screens
                        Rbmdxcs: Steel wire fabrics
                        Rbmdxct: Textiles
                            Rbmdxctf: Textile fabrics
                        Rbmdxcw: Welded wire fabrics
                        Rbmdxcx: Woven materials
                            Rbmdxcxf: Woven fabrics
                    Rbmdxf: Fibers
                        Rbmdxfb: Aramid fibers
                        Rbmdxfc: Carbon fibers
                        Rbmdxfg: Glass fibers
                        Rbmdxfm: Metal fibers
                        Rbmdxfo: Optical fibers
                        Rbmdxfp: Polymer fibers
                        Rbmdxfs: Steel fibers
                        Rbmdxft: Synthetic fibers
                        Rbmdxfv: Vulcanized fibers
                    Rbmdxm: Particles
                        Rbmdxmf: Fines (Materials)
                        Rbmdxmg: Granular materials
                        Rbmdxmm: Particulates
                        Rbmdxmp: Pellets
                        Rbmdxms: Powders
                        Rbmdxmv: Screenings
                    Rbmdxn: Pipe and tubing
                        Rbmdxnp: Pipe
                            Rbmdxnpc: Concrete pipe
                                Rbmdxnpcr: Reinforced concrete pipe
                            Rbmdxnpe: Corrugated pipe
                            Rbmdxnpg: Culvert pipe
                            Rbmdxnph: Cured in place pipe
                            Rbmdxnpj: Drain pipe
                                Rbmdxnpjt: Traps (Drain pipe)
                            Rbmdxnpk: Metal pipe
                                Rbmdxnpks: Steel pipe
                            Rbmdxnpm: Perforated pipe
                            Rbmdxnpp: Plastic pipe
                            Rbmdxnpr: Riser pipe
                            Rbmdxnps: Sewer pipe
                            Rbmdxnpw: Water pipe
                        Rbmdxnt: Tubing
                    Rbmdxq: Rope, wire and cable
                        Rbmdxqc: Cables
                            Rbmdxqcs: Suspension cables
                        Rbmdxqr: Rope
                            Rbmdxqrs: Synthetic rope
                            Rbmdxqrw: Wire rope
                        Rbmdxqw: Wire
                            Rbmdxqwe: Electric wire
                            Rbmdxqwg: Filaments
                            Rbmdxqwm: Long span
                            Rbmdxqws: Steel wire
                    Rbmdxs: Sheets and plates
                        Rbmdxsd: Diaphragms (Engineering)
                        Rbmdxsm: Laminates
                            Rbmdxsmb: Bimetals
                        Rbmdxsn: Paper
                        Rbmdxsp: Particle board
                        Rbmdxsq: Plates (Engineering)
                            Rbmdxsqc: Anchor plates
                            Rbmdxsqe: Bolsters
                            Rbmdxsqg: Gusset plates
                            Rbmdxsqj: Orthotropic plates
                            Rbmdxsqm: Plate metal
                            Rbmdxsqp: Platens
                            Rbmdxsqq: Splice plates
                            Rbmdxsqr: Steel plates
                            Rbmdxsqs: Stiffened plates
                            Rbmdxsqt: Stiffeners (Plates)
                                Rbmdxsqtm: Longitudinal stiffeners
                                Rbmdxsqtt: Transverse stiffeners
                            Rbmdxsqx: Thin plates
                            Rbmdxsqy: Welded plates
                        Rbmdxsr: Sheathing
                        Rbmdxss: Sheets
                            Rbmdxssb: Foil
                            Rbmdxssd: Panels
                            Rbmdxssf: Separators
                                Rbmdxssfr: Raised separators
                            Rbmdxssm: Sheet metal
                            Rbmdxssn: Strip metal
                            Rbmdxssp: Sheet molding compounds
                            Rbmdxsss: Steel sheets
                        Rbmdxst: Siding
                    Rbmdxt: Materials by surface characteristics
                        Rbmdxtb: Coarse grained materials
                        Rbmdxtf: Coated materials
                            Rbmdxtfc: Cold coated materials
                            Rbmdxtfh: Hot coated materials
                    Rbmdxu: Tile and shingles
                        Rbmdxus: Shingles
                        Rbmdxut: Tile
                            Rbmdxutd: Drain tile
                    Rbmdxw: Webbing
                        Rbmdxwm: Wire mesh
                Rbmdy: Materials by chemical properties, composition & structure
                    Rbmdyb: Materials by direction of measurement properties
                        Rbmdybb: Anisotropic materials
                        Rbmdybj: Isotropic materials
                    Rbmdyc: Cylindrical bodies
                    Rbmdye: Elastic bodies
                        Rbmdyev: Viscoelastic materials
                    Rbmdyf: Expanded materials
                    Rbmdyg: Extrudates
                    Rbmdyh: Foams and emulsions
                        Rbmdyhe: Emulsions
                            Rbmdyheb: Asphalt emulsions
                        Rbmdyhf: Foams
                            Rbmdyhfb: Foamed materials
                            Rbmdyhff: Foaming agents
                            Rbmdyhfh: High expansion foams
                            Rbmdyhfp: Plastic foams
                            Rbmdyhfr: Polyurethane foams
                    Rbmdyj: Impurities
                    Rbmdyk: Oils
                        Rbmdyke: Engine oils
                        Rbmdykf: Flux oil
                        Rbmdykg: Heavy oils
                        Rbmdykj: Lubricating oils
                        Rbmdykm: Mineral oils
                        Rbmdykp: Multigrade oils
                        Rbmdykr: Oil additives
                        Rbmdykt: Shale oil
                        Rbmdykv: Vegetable oils
                            Rbmdykvh: Linseed oil
                    Rbmdys: Materials by strength or resistance to chemical action
                        Rbmdysb: Chemical resistant materials
                        Rbmdysc: Cohesionless materials
                        Rbmdyse: Corrosion resistant materials
                        Rbmdysg: Fiber reinforced materials
                        Rbmdysh: Hard materials
                        Rbmdysj: High strength materials
                        Rbmdysm: Impervious materials
                        Rbmdyss: Stabilized materials
                    Rbmdyt: Materials at high or low temperatures
                        Rbmdytc: Calcines
                        Rbmdytf: Cryogenic materials
                        Rbmdyth: Heat resistant materials
                        Rbmdytm: Low temperature materials
                        Rbmdytr: Refractory materials
                    Rbmdyw: Materials by weight
                        Rbmdywm: Lightweight materials
            Rbmn: Materials by function
                Rbmnb: Abrasives
                    Rbmnbg: Grits
                Rbmnd: Adhesives
                    Rbmnda: Adhesive tape
                    Rbmndb: Binders
                        Rbmndbc: Antistrip additives
                        Rbmndbh: Bituminous binders
                        Rbmndbq: Hydraulic binders
                    Rbmndc: Fluxes
                    Rbmndd: Glue
                    Rbmndf: Grout
                        Rbmndfc: Cement grouts
                        Rbmndfd: Chemical grouts
                    Rbmndj: Mortar
                        Rbmndjc: Cement mortars
                        Rbmndjp: Patching mortar
                    Rbmndn: Pastes
                        Rbmndnc: Cement paste
                    Rbmnds: Solder
                Rbmne: Cleansers
                    Rbmned: Detergents
                    Rbmnef: Disinfectants
                    Rbmnes: Soap
                Rbmnf: Coatings, fillers and paints
                    Rbmnfc: Coatings
                        Rbmnfcb: Abrasion resistant coatings
                        Rbmnfcc: Aluminum coatings
                        Rbmnfcf: Anticorrosion coatings
                        Rbmnfch: Antifouling coatings
                        Rbmnfcj: Bituminous coatings
                        Rbmnfcm: Ceramic coatings
                        Rbmnfcp: Films (Coatings)
                            Rbmnfcpt: Thin films
                        Rbmnfcr: Metal coatings
                        Rbmnfcs: Organic coatings
                        Rbmnfcu: Plastic coatings
                            Rbmnfcue: Epoxy coatings
                            Rbmnfcur: Rubber coatings
                        Rbmnfcv: Protective coatings
                        Rbmnfcw: Toxic coatings
                        Rbmnfcx: Zinc coatings
                    Rbmnfd: Fillers (Materials)
                        Rbmnfdj: Joint fillers
                        Rbmnfdk: Limestone fillers
                        Rbmnfdm: Mineral fillers
                    Rbmnff: Finishes
                        Rbmnffe: Facings
                    Rbmnfj: Moisture barriers
                    Rbmnfn: Paint
                        Rbmnfnb: Aluminum paint
                        Rbmnfne: Enamels
                        Rbmnfnk: Lead based paint
                        Rbmnfnp: Pigments
                        Rbmnfnr: Reflectorized paint
                        Rbmnfns: Tack coats
                        Rbmnfnt: Traffic paint
                        Rbmnfnu: Underwater paint
                        Rbmnfny: Zinc rich paint
                    Rbmnfp: Penetrants
                    Rbmnfq: Plugs (Fillers)
                    Rbmnfr: Primers (Materials)
                    Rbmnfs: Sealing compounds
                        Rbmnfsc: Chip seals
                        Rbmnfsj: Joint sealers
                        Rbmnfss: Slurry seals
                    Rbmnfu: Varnish
                    Rbmnfv: Waterproofing materials
                        Rbmnfvf: Flashing
                        Rbmnfvr: Water repellents
                    Rbmnfw: Waxes
                    Rbmnfx: Wood preservatives
                Rbmng: Colorants
                    Rbmngd: Dyes
                    Rbmngj: Ink
                    Rbmngm: Marking materials
                Rbmnh: Coolants
                    Rbmnhb: Antifreeze
                    Rbmnhd: Brines
                    Rbmnhf: Cooling water
                    Rbmnhn: Nuclear reactor coolants
                    Rbmnhr: Refrigerants
                Rbmni: Cushioning materials
                    Rbmnie: Energy absorbing materials
                Rbmnj: Deicing chemicals
                    Rbmnjc: Calcium chloride
                    Rbmnjf: Calcium magnesium acetate
                    Rbmnjs: Sodium chloride
                Rbmnk: Fasteners
                    Rbmnkb: Bolts
                        Rbmnkbb: Anchor bolts
                        Rbmnkbr: Rockbolts
                    Rbmnkc: Chains
                    Rbmnkd: Cotters
                        Rbmnkdp: Cotter pins
                    Rbmnkf: Dowels (Fasteners)
                    Rbmnkh: Fastenings
                    Rbmnki: Locks (Fasteners)
                    Rbmnkk: Hinges
                    Rbmnkl: Lugs
                    Rbmnkm: Nails
                    Rbmnkn: Nuts (Fasteners)
                    Rbmnkp: Pins
                    Rbmnkr: Rivets
                    Rbmnks: Screws
                    Rbmnkt: Spikes
                    Rbmnkv: Stud connectors
                Rbmnm: Materials by flammability
                    Rbmnmc: Fire resistant coatings
                    Rbmnme: Fire extinguishing agents
                    Rbmnmn: Nonflammable materials
                    Rbmnmp: Fireproof materials
                    Rbmnmr: Fire retardants
                    Rbmnms: Fire resistant materials
                    Rbmnmy: Flammable materials
                Rbmnn: Friction materials
                    Rbmnng: Grease
                    Rbmnnm: Lubricants
                    Rbmnns: Surface active agents
                Rbmnt: Insulating materials
                    Rbmntb: Acoustic materials
                        Rbmntbs: Sound insulating materials
                    Rbmnte: Electric insulating materials
                        Rbmnted: Dielectric materials
                    Rbmnth: Heat insulating materials
                        Rbmnthb: Insulation blankets
                Rbmnu: Linings
                Rbmnv: Plasticizers
                    Rbmnvp: Superplasticizers
                Rbmnx: Sorbents
                    Rbmnxb: Oil sorbents
                    Rbmnxe: Absorbents
                        Rbmnxed: Driers (Materials)
                        Rbmnxep: Porous materials
                    Rbmnxg: Adsorbents
                Rbmny: Wedges
            Rbmu: Materials by end use
                Rbmue: Structural materials
                    Rbmueb: Bearing materials
                    Rbmued: Reinforcing materials
                    Rbmuej: Materials in specific structural applications
                        Rbmuejp: Paving materials
                            Rbmuejpc: Cold mix paving mixtures
                            Rbmuejpf: Warm mix paving mixtures
                            Rbmuejph: Hot mix paving mixtures
                            Rbmuejps: Subbase materials
                            Rbmuejpt: Subgrade materials
                Rbmuh: Electronic materials
                    Rbmuhf: Ferroelectric materials
                        Rbmuhfp: Piezoelectric materials
                    Rbmuhk: Magnetic materials
                        Rbmuhkf: Ferromagnetic materials
                    Rbmuhm: Microelectronic materials
                        Rbmuhmn: Nanostructure materials
                    Rbmuhp: Optoelectronic materials
                    Rbmuht: Thermoelectric materials
                    Rbmuhv: Electronic materials by conductivity
                        Rbmuhvg: Semiconductors
                            Rbmuhvgs: Superlattices
                            Rbmuhvgt: Transistor materials
                        Rbmuhvm: Conducting materials
                            Rbmuhvmp: Photoconducting materials
                        Rbmuhvs: Superconductors
                            Rbmuhvsc: Composite superconductors
                Rbmuj: Optical materials
                    Rbmuje: Electrooptic materials
                    Rbmujf: Fiberoptic materials
                    Rbmujh: Holographic materials
                    Rbmujm: Laser materials
                    Rbmujp: Luminous materials
                    Rbmujr: Optical fibers
                    Rbmuju: Photographic materials
                    Rbmujv: Reflectorized materials
                        Rbmujvr: Retroreflectors
                    Rbmujx: Refractive materials
                        Rbmujxp: Photorefractive materials
                Rbmum: Industrial materials
                    Rbmumr: Raw materials
                    Rbmums: Strategic materials
                    Rbmumt: Materials in specific industries
                        Rbmumtc: Agricultural chemicals
                            Rbmumtcf: Fertilizers
                            Rbmumtcg: Herbicides
                            Rbmumtcj: Insecticides
                                Rbmumtcjn: Nicotine
                            Rbmumtcp: Pesticides
                            Rbmumtcs: Soil sterilants
                        Rbmumtd: Biological materials
                        Rbmumte: Biomedical materials
                        Rbmumtg: Drilling fluids
                        Rbmumtp: Packaging materials
                        Rbmumtt: Transportation materials
                            Rbmumttb: Aerospace materials
                            Rbmumtth: Road materials
                                Rbmumtths: Road marking materials
                                    Rbmumtthss: Striping materials
                                    Rbmumtthsu: Road marking tapes
                            Rbmumttr: Railroad materials
                                Rbmumttrf: Rail fasteners
                Rbmur: Engine materials
                    Rbmure: Engine oils
                    Rbmurw: Working fluids
                        Rbmurws: Steam
                Rbmuv: Vehicular materials
                    Rbmuvb: Aircraft materials
                    Rbmuvc: Automotive materials
                    Rbmuvs: Shipbuilding materials
                    Rbmuvt: Spacecraft materials
                        Rbmuvtb: Ablative materials
            Rbmv: Engineered materials
                Rbmvs: Smart materials
                Rbmvw: Synthetics
            Rbmy: Materials by source
                Rbmym: Local materials
    Rk: Properties of materials
        Rkb: Acoustic properties
            Rkbf: Acoustic impedance
            Rkbj: Acoustic signature
            Rkbn: Damping capacity
            Rkbq: Loudness
        Rkc: Chemical properties
            Rkcb: Chemical composition
                Rkcbb: Chemical composition by material content
                    Rkcbba: Air content
                    Rkcbbb: Ash content
                    Rkcbbg: Asphalt content
                    Rkcbbj: Binder content
                    Rkcbbm: Cement content
                        Rkcbbmf: Cement factor
                    Rkcbbn: Chloride content
                    Rkcbbq: Chlorine content
                    Rkcbbt: Organic content
                Rkcbf: Heterogeneity
                Rkcbh: Homogeneity
                Rkcbs: Salinity
            Rkcf: Chemical reactivity
                Rkcfb: Biodegradability
                Rkcff: Boiling point
                Rkcfj: Bond strength (Chemistry)
                Rkcfn: Corrosion resistance
                Rkcfp: Instability
                Rkcfr: Stability (Chemistry)
                Rkcfu: Stoichiometry
                Rkcfv: Volatility
                Rkcfw: Weather resistance
            Rkcg: Combustion efficiency
            Rkch: Concentration (Chemistry)
            Rkcj: Drag factor (Chemistry)
            Rkcm: Flammability
                Rkcmc: Cetane number
                Rkcmk: Fire resistance
                Rkcms: Flash point
            Rkco: Octane number
            Rkcp: pH value
                Rkcpf: Acidity
                Rkcpr: Alkalinity
            Rkcq: Polymorphism (Chemistry)
            Rkcs: Solubility
            Rkct: Thixotropy
            Rkcv: Toxicity
            Rkcx: Turbidity
        Rke: Electrical properties
            Rkec: Capacitance
            Rked: Dielectric properties
            Rkef: Electrical conductivity
                Rkefp: Photoconductivity
                Rkefs: Superconductivity
            Rkeg: Electrical impedance
            Rkeh: Electrical resistivity
                Rkehs: Skin resistance
            Rkek: Inductance
            Rkeo: Peak value (Electricity)
            Rkep: Power factor (Electricity)
            Rkeq: Power level (Electricity)
            Rker: Refractivity
            Rket: Transfer characteristics
        Rkf: Electromagnetic properties
            Rkfb: Bandwidth
            Rkfe: Electromagnetic compatibility
            Rkfg: Frequency response
            Rkfn: Magnetic properties
                Rkfng: Magnetic induction
            Rkft: Transmittance (Electromagnetism)
        Rkm: Mechanical properties
            Rkma: Strength of materials
                Rkmaa: Adhesive strength
                Rkmab: Bond strength (Materials)
                    Rkmabw: Weld strength
                Rkmac: Cohesive strength
                Rkmad: Collapse strength
                Rkmae: Compressive strength
                Rkmaf: Cyclic strength
                Rkmag: Fatigue strength
                Rkmah: Field strength
                Rkmaj: Flexural strength
                Rkmak: High strength
                Rkmal: Longitudinal strength
                Rkmam: Residual strength
                Rkmar: Shear strength
                    Rkmarr: Residual shear strength
                    Rkmaru: Undrained shear strength
                Rkmas: Tear strength
                Rkmat: Tensile strength
                Rkmau: Torsional strength
                Rkmav: Transverse strength
                Rkmaw: Ultimate strength
                Rkmax: Undrained strength
                Rkmay: Yield strength
            Rkmb: Bearing capacity
                Rkmbm: Load limits
                Rkmbt: Trafficability
            Rkmc: Collapse properties
            Rkmd: Compressibility
            Rkme: Dilatancy
            Rkmf: Durability
            Rkmg: Eccentricity
            Rkmh: Elasticity (Mechanics)
                Rkmhc: Consistency
                Rkmhh: Hydroelasticity
                Rkmhm: Linear elasticity
                Rkmhn: Orthotropic
                Rkmhp: Photoelasticity
                Rkmht: Thermoelasticity
                Rkmhv: Viscoelasticity
            Rkmi: Friability
            Rkmj: Hardness
                Rkmjb: Abrasion resistance
                Rkmjp: Penetration resistance
                Rkmjs: Puncture resistance
                Rkmjw: Work hardening
            Rkmk: Inertia (Mechanics)
                Rkmkk: Resistance (Mechanics)
            Rkml: Plasticity
                Rkmlb: Brittleness
                    Rkmlbe: Embrittlement
                        Rkmlbeb: Acid brittleness
                    Rkmlbf: Fracture properties
                Rkmlf: Creep properties
                Rkmlm: Ductility
                Rkmlq: Elastoplasticity
                Rkmls: Rheological properties
                Rkmlt: Slip resistance
                Rkmlv: Toughness
                Rkmly: Viscoplasticity
            Rkmm: Resilience
            Rkmn: Shear properties
            Rkmo: Shock resistance
            Rkmp: Static stability
            Rkmq: Stiffness
                Rkmqf: Flexibility
            Rkmr: Tensile properties
            Rkmu: Workability
            Rkmy: Mechanical properties by mathematical limits or values
                Rkmya: Atterberg limits
                    Rkmyam: Liquid limits
                    Rkmyap: Plastic limit
                    Rkmyas: Shrinkage limit
                Rkmyb: Bulk modulus
                Rkmyd: Coefficient of friction
                    Rkmydc: Angle of repose
                        Rkmydcc: Angle of rest
                Rkmye: Coefficient of internal friction
                Rkmyg: Compliance constant
                Rkmyh: Deformation curve
                    Rkmyhy: Yield point
                Rkmyi: Design load
                    Rkmyim: Load factor
                Rkmyj: Elastic limit
                Rkmyk: Fatigue limit
                Rkmyl: Hygroscopic coefficient
                Rkmyn: Influence lines
                Rkmyo: Mechanical impedance
                Rkmyp: Modulus of deformation
                Rkmyq: Modulus of elasticity
                    Rkmyqd: Dynamic modulus of elasticity
                Rkmyr: Modulus of resilience
                Rkmys: Modulus of rupture
                Rkmyt: Plasticity index
                Rkmyu: Poisson ratio
                Rkmyv: Shear modulus
                Rkmyw: Stress ratio
                Rkmyx: Young's modulus
                Rkmyy: Mechanical properties of pavements expressed numerically
                    Rkmyyc: California bearing ratio
                    Rkmyyf: Coefficient of subgrade reaction
                    Rkmyyj: Drainage coefficient (Pavements)
                    Rkmyym: Layer coefficient (Pavements)
                    Rkmyys: Structural number (Pavements)
                    Rkmyyt: Traffic equivalence factor
        Rko: Optical properties
            Rkoa: Angle of incidence
            Rkob: Brightness
            Rkoc: Color
                Rkocb: Blue
                Rkocg: Green
                Rkoco: Orange
                Rkocr: Red
                Rkocw: White
                Rkocy: Yellow
            Rkoe: Contrast
            Rkof: Fluorescence
            Rkok: Luminosity factor
            Rkom: Luminous intensity
                Rkomm: Luminance
            Rkop: Opacity
                Rkopp: Optical density
            Rkor: Reflectivity
                Rkorr: Retroreflectivity
            Rkot: Transparence
        Rkp: Physical properties
            Rkpd: Density
                Rkpdb: Bulk density
                Rkpdc: Compactibility
                Rkpdd: Dry density
                Rkpdf: Field density
                Rkpdh: High density
                Rkpdj: In place density
                Rkpdk: Low density
                Rkpds: Specific gravity
                Rkpdw: Wet density
            Rkpj: Direction of measurement properties
                Rkpjb: Anisotropy (Physics)
                Rkpjj: Isotropy
            Rkpk: Microstructure
            Rkpm: Moisture content
                Rkpmd: Dryness
                Rkpmp: Percent saturation
            Rkpn: Molecular structure
            Rkpp: Porosity
            Rkps: Steady state
            Rkpt: Texture
                Rkpth: Grain shape (Geology)
                Rkptj: Grain size (Geology)
                Rkptk: Macrotexture
                Rkptm: Microtexture
                Rkptp: Pore size distribution
                Rkptr: Roughness
                Rkpts: Shape
                    Rkptsb: Angularity
                    Rkptsd: Asymmetry
                    Rkptst: Thinness
                Rkptt: Skid resistance
                Rkptu: Slipperiness
                Rkptw: Smoothness
                Rkpty: Void ratios
            Rkpv: Volume
                Rkpvs: Size
                    Rkpvsd: Depth
                    Rkpvsf: Fineness
                    Rkpvsh: Height
                    Rkpvsm: Length
                    Rkpvss: Specific surface
                    Rkpvsw: Width
                Rkpvt: Thickness
            Rkpw: Weight
                Rkpwg: Gross weight
                Rkpwk: Mass
                Rkpwm: Molecular weight
                Rkpwu: Unsprung weight
        Rkr: Physicochemical properties
            Rkrb: Absorptivity
            Rkrd: Drying rate
            Rkre: Gas permeability (Concrete)
            Rkrh: Hydrophobic properties
            Rkrp: Permeability
            Rkrt: Swelling index
        Rkt: Thermal properties
            Rkta: Adiabatic conditions
            Rktb: Diffusivity
            Rkte: Enthalpy
                Rkteh: Heat of hydration
                Rktes: Heat of solution
            Rktf: Entropy (Statistical mechanics)
            Rktg: Freeze thaw durability
            Rkth: Frost susceptibility
            Rktk: Specific heat
            Rktm: Temperature
                Rktmc: Isotherms
                Rktmh: High temperature
                Rktmm: Low temperature
                Rktms: Surface temperature
                Rktmt: Temperature points
                    Rktmtf: Freezing point
                    Rktmtm: Melting point
                    Rktmts: Softening point
                    Rktmtt: Transition point
            Rktp: Thermal conductivity
            Rktt: Thermal resistance
            Rktv: Thermal stability
            Rktw: Transport properties (Physics)
        Rkw: Properties of fluids
            Rkwd: Dew point
            Rkwf: Flow fields
                Rkwff: Flow visualization
            Rkwg: Fluidity
                Rkwgm: Low temperature fluidity
            Rkwj: Hydraulic properties
                Rkwjg: Hydraulic gradient
            Rkwk: Oxygen content
            Rkwm: Permeability coefficient
            Rkwp: Pressure resistance
            Rkwr: Roughness coefficient
            Rkwt: Turbidity
            Rkwv: Viscosity
S: Physical phenomena
    Sa: Laws of physics
        Sab: Boussinesq equation
        Sag: Conservation of mass and energy
        Sak: Conservation of momentum
        Sal: Equations of motion
        Sam: Darcy's law
        Sao: Froude number
        Sap: Newton's law of gravitation
        Saq: Newton's equations of motion
        Sav: Reynolds number
        Saw: Terzaghi's rule
        Say: Wave equations
    Sb: Sound
        Sbb: Acoustic emission
        Sbf: Acoustic scattering
        Sbh: Acoustic waves
            Sbhd: Aerodynamic noise
                Sbhds: Sonic boom
            Sbhr: Acoustic radiation
                Sbhrf: Far field
                Sbhrn: Near field
        Sbi: Directivity pattern
        Sbj: Effective sound pressure
            Sbjs: Sound level
        Sbm: Harmonics
        Sbp: Infrasound
        Sbr: Pitch (Acoustics)
        Sbt: Sound attenuation
            Sbts: Sound absorption
        Sbv: Sound transmission
            Sbvr: Reverberation
            Sbvs: Sound intensity
        Sbw: Speed of sound
        Sbx: Ultrasonic waves
            Sbxr: Ultrasonic radiation
        Sby: Underwater sound
    Sc: Chemical reactions and processes
        Scc: Chemical reactions
            Scca: Catalysis
            Sccb: Combination (Chemistry)
            Sccc: Detonation
            Sccd: Explosions
            Scce: Fermentation
            Sccf: Hydration
            Sccg: Hydrogenation
                Sccgb: Coal hydrogenation
            Scch: Hydrolysis
            Scci: Ion exchange
                Sccic: Cation exchange
            Sccj: Neutralization
            Sccm: Oxidation
                Sccmc: Combustion
                    Sccmcf: Fluidized bed combustion
                    Sccmcy: Manifestations of combustion
                        Sccmcyf: Fire
                        Sccmcyh: Flames
                            Sccmcyhf: Flame propagation
            Sccn: Photochemical reactions
            Sccp: Polymerization
            Sccr: Reduction (Chemistry)
            Sccs: Replacement (Chemistry)
            Scct: Synthesis (Chemistry)
            Sccv: Vulcanization
            Sccw: Reactions in asphalt
                Sccwb: Asphalt hardening
            Sccy: Reactions in concrete
                Sccya: Air entrainment
                Sccyb: Alkali aggregate reactions
                Sccyc: Alkali carbonate reactions
                Sccye: Alkali silica reactions
                Sccyh: Concrete hardening
                Sccyp: Pozzolanic action
                Sccyr: Scaling (Concrete)
                Sccys: Setting (Concrete)
        Scp: Chemical processes
            Scpa: Activation (Chemistry)
            Scpb: Aggregation (Chemistry)
            Scpc: Association (Chemistry)
            Scpd: Carbonation
            Scpe: Carbonization
            Scpf: Chemical bond
            Scpg: Chlorination
            Scph: Corrosion
                Scphb: Cavitation erosion
                Scphe: Electrochemical corrosion
                    Scphes: Stray current corrosion
                Scphf: Fretting corrosion
                Scphg: Galvanic corrosion
                Scphp: Pitting
                Scphr: Rusting
                Scphv: Shelling (Metals)
                Scphx: Stress corrosion
            Scpi: Crystallization
                Scpin: Nucleation
            Scpj: Decomposition
            Scpk: Desulfurization
            Scpl: Dilution
            Scpm: Dissociation (Chemistry)
            Scpn: Dissolution
                Scpnm: Leaching
            Scpo: Distillation
            Scpp: Electrochemical processes
                Scppb: Anodic polarization
                Scppm: Electrolysis
                Scppp: Electroosmosis
            Scpq: Gasification
            Scpr: Ignition
            Scps: Ionization
            Scpt: Isolation (Chemistry)
            Scpu: Osmosis
            Scpv: Photolysis
            Scpw: Precipitation (Chemistry)
                Scpwc: Coagulation
            Scpx: Pyrolysis
            Scpy: Solvation
    Se: Electricity
        Sea: Accelerating potential
        Seb: Attenuation (Electricity)
        See: Conduction
        Seg: Electric current
            Segb: Alternating current
            Segd: Direct current
            Segg: Eddy currents
            Segr: Short circuits
            Segs: Stray currents
        Sej: Electric discharge
            Seje: Electric arcs
            Sejs: Sparks
        Sem: Electric fields
        Sep: Electric potential
            Sepv: Voltage
                Sepvh: High voltage
                Sepvm: Low voltage
                Sepvp: Overvoltage
        Seq: Electric power
            Seql: Power loss
            Seqo: Power output
        Ser: Electrostatics
        Set: Intensity (Electricity)
        Seu: Phase shift (Electricity)
        Sev: Piezoelectricity
            Sevv: Voltage regulation
        Sew: Resistance (Electricity)
            Sewd: Dynamic resistance
        Sex: Resonance
            Sexf: Resonance frequency
                Sexfn: Natural frequency
        Sey: Wall effect
    Sf: Electromagnetism
        Sff: Electromagnetic fields
            Sffp: Photons
        Sfj: Electromagnetic induction
        Sfr: Electromagnetic radiation
            Sfrw: Electromagnetic waves
                Sfrwa: Electromagnetic waves by wavelength
                    Sfrwaa: Sound
                    Sfrwab: Radio waves
                    Sfrwaf: Microwaves
                    Sfrwah: Millimeter waves
                    Sfrwaj: Infrared radiation
                    Sfrwam: Light
                    Sfrwap: Ultraviolet light
                    Sfrwas: X rays
                    Sfrwav: Gamma rays
                    Sfrway: Cosmic rays
                Sfrwb: Electromagnetic wave phenomena
                    Sfrwbb: Electromagnetic wave propagation
                        Sfrwbbr: Radio wave propagation
                    Sfrwbd: Diffraction
                    Sfrwbe: Doppler effect
                        Sfrwbed: Doppler shift
                    Sfrwbf: Frequency (Electromagnetism)
                        Sfrwbfm: Audio frequency
                            Sfrwbfmv: Voice frequency
                        Sfrwbfr: Radio frequency
                            Sfrwbfrb: Broadband
                            Sfrwbfrc: Very low frequency
                            Sfrwbfrg: Low frequency
                            Sfrwbfrh: Medium frequency
                            Sfrwbfrj: High frequency
                            Sfrwbfrm: Very high frequency
                            Sfrwbfrs: Ultrahigh frequency
                                Sfrwbfrsm: L band
                                Sfrwbfrss: S band
                            Sfrwbfrw: Superhigh frequency
                                Sfrwbfrwk: Ku band
                    Sfrwbp: Polarization
                        Sfrwbpg: Pulses
                    Sfrwbq: Radiation patterns
                        Sfrwbqs: Frequency spectra
                    Sfrwbr: Reflection
                        Sfrwbrr: Radar reflection
                            Sfrwbrrr: Radar cross section
                        Sfrwbrt: Retroreflection
                    Sfrwbs: Refraction
                    Sfrwbt: Scattering
                        Sfrwbtb: Backscattering
                Sfrws: Electromagnetic wave properties
                    Sfrwsb: Amplitude (Physics)
                    Sfrwsp: Power spectra
                    Sfrwsw: Wavelength
        Sfv: Electromagnetic spectrum
        Sfx: Particle beams
            Sfxe: Electron beams
            Sfxm: Laser beams
            Sfxr: Radio beams
                Sfxrr: Radar beams
            Sfxx: X rays
                Sfxxr: X ray fluorescence
    Sm: Mechanics
        Sma: Attenuation (Physics)
        Smb: Deformation
            Smbb: Bending
                Smbbm: Bending moments
                Smbbs: Bending stress
            Smbc: Buckling
                Smbcb: Blowup (Pavements)
            Smbe: Creep
                Smber: Relaxation (Mechanics)
            Smbj: Distortion (Structures)
            Smbk: Elastic deformation
                Smbkb: Aeroelasticity
                Smbkc: Cratering
                Smbkg: Deflection
            Smbm: Flexure
            Smbp: Plastic deformation
            Smbq: Plastic flow
            Smbr: Rutting
                Smbrc: Corrugations (Defects)
            Smbs: Strain (Mechanics)
                Smbss: Shear strain
            Smbv: Tension
            Smbw: Torsion
            Smbx: Warpage
        Smc: Degrees of freedom
            Smcc: Constraints
        Smd: Dynamics
            Smdf: Fluid dynamics
                Smdfb: Aerodynamics
                    Smdfbd: Downwash
                    Smdfbs: Shock (Mechanics)
                        Smdfbss: Shock waves
                            Smdfbssb: Bow waves
                Smdfc: Cavitation (Mechanics)
                Smdfd: Drag
                    Smdfdb: Air resistance
                    Smdfds: Sound barrier
                    Smdfdw: Wave drag
                Smdff: Flow
                    Smdffa: Boundary layer flow
                        Smdffas: Boundary layer separation
                    Smdffb: Flow by speed
                        Smdffbb: Subsonic flow
                        Smdffbk: Critical flow
                        Smdffbm: Potential flow
                        Smdffbp: Supersonic flow
                        Smdffbv: Critical velocity
                    Smdffc: Compressible flow
                    Smdffd: Confined flow
                        Smdffdc: Channel flow
                            Smdffdcc: Critical depth
                            Smdffdce: Constrictions
                        Smdffdp: Pipe flow
                        Smdffdr: Queuing
                        Smdffdt: Flow resistance
                        Smdffdv: Vapor lock
                    Smdffe: Convection (Fluid mechanics)
                    Smdfff: Flow equations
                    Smdffg: Infiltration
                    Smdffi: Laminar flow
                        Smdffis: Shear rate
                    Smdffk: Multidimensional flow
                        Smdffkb: Three dimensional flow
                        Smdffkt: Two dimensional flow
                    Smdffl: Multiphase flow
                        Smdfflt: Two phase flow
                    Smdffm: Nonnewtonian flow
                    Smdffn: Nonuniform flow
                    Smdffo: Overflows
                    Smdffp: Overtopping
                    Smdffq: Percolation
                    Smdffr: Seepage
                    Smdffs: Slip (Fluid mechanics)
                    Smdfft: Transitional flow
                    Smdffu: Turbulence
                    Smdffv: Viscous flow
                        Smdffvb: Bleeding (Pavements)
                    Smdffw: Vortices
                        Smdffwe: Eddies
                        Smdffwt: Vortex shedding
                    Smdffx: Wakes
                    Smdffy: Unsteady flow
            Smdg: Fluid resistance
                Smdgw: Wave resistance
            Smdh: Hydrodynamics
            Smdj: Friction
                Smdjb: Abrasion
                Smdjj: Internal friction
                Smdjr: Rolling friction
                    Smdjrr: Rolling resistance
                Smdjs: Skin friction
                    Smdjsn: Negative skin friction
                Smdjt: Sliding friction
                Smdju: Traction
                Smdjw: Wall friction
            Smdm: Impact
                Smdmk: Impact loads
                Smdms: Slamming
            Smdp: Motion
                Smdpb: Acceleration (Mechanics)
                    Smdpbm: Lateral acceleration
                Smdpd: Deceleration
                Smdpf: Falling
                    Smdpff: Free fall
                Smdpk: Kinetics
                Smdpn: Oscillation
                Smdpp: Pitch (Dynamics)
                    Smdppm: Pitching moment
                Smdpq: Rocking
                Smdpr: Rolling
                Smdps: Rotation
                    Smdpst: Torque
                    Smdpsy: Yaw
                        Smdpsyh: Hunting (Dynamics)
                Smdpt: Splashing
                    Smdpts: Sloshing
                Smdpv: Velocity
                    Smdpvc: Angular velocity
                        Smdpvcc: Angular acceleration
                    Smdpvs: Speed
                        Smdpvsm: Mach number
                        Smdpvss: Supersonic speed
            Smdr: Rolling contact
                Smdrs: Polishing (Aggregates)
            Smdv: Vibration
                Smdvd: Damping (Physics)
                Smdvf: Flutter (Aeronautics)
                Smdvm: Mechanical vibration
                Smdvr: Random vibration
        Sme: Energy
            Smeb: Burning rate
            Smed: Dissipation
            Smee: Energy balance
            Smef: Energy conversion
                Smefe: Energy absorption
            Smem: Energy levels
            Smen: Energy transfer
            Smep: Power
                Smeph: Horsepower
            Smes: Specific energy
            Smey: Work (Mechanics)
                Smeyd: Free energy
                Smeyf: Friction losses
                Smeyk: Kinetic energy
                    Smeykr: Regenerative braking
                Smeyp: Potential energy
                    Smeyps: Stiffness matrix
        Smf: Failure
            Smfc: Collapse
            Smfd: Cracking
                Smfdb: Types of cracking
                    Smfdbp: Microcracking
                    Smfdbs: Stress cracking
                        Smfdbsf: Fatigue cracking
                Smfdp: Pavement cracking
                    Smfdpb: Cracking of asphalt concrete pavements
                        Smfdpbb: Alligator cracking
                        Smfdpbe: Block cracking
                        Smfdpbr: Reflection cracking
                    Smfdpm: Cracking of concrete pavements
                        Smfdpmd: D cracking
                        Smfdpmm: Longitudinal cracking
                        Smfdpmt: Transverse cracking
                Smfdr: Rock fracture
                    Smfdrj: Rock jointing
                    Smfdrs: Spalling
            Smfe: Debonding
                Smfeb: Blistering
                Smfed: Delamination
            Smff: Fatigue (Mechanics)
            Smfh: Fracture mechanics
                Smfhc: Cleavage fracture
                Smfhs: Slaking
            Smfp: Overturning
            Smfr: Segregation (Aggregates)
            Smfs: Stripping (Pavements)
            Smft: Tearing
                Smftb: Blowouts
        Smh: Fluid mechanics
            Smhf: Free surface
            Smhh: Friction factor
            Smhj: Hydraulic jump
        Smi: Force
            Smia: Buoyancy
            Smib: Centrifugal force
            Smic: Centripetal force
            Smid: Drag forces
            Smif: Cohesion
            Smih: Impulses (Mechanics)
            Smij: Inertial forces
            Smik: Internal forces
            Smim: Loads
                Smima: Aerodynamic force
                    Smimam: Aerodynamic lift
                        Smimamg: Ground effect
                        Smimamm: Lift drag ratio
                    Smimas: Stall
                    Smimau: Thrust
                        Smimaub: Blade loading
                    Smimaw: Wing loading
                Smimb: Axial loads
                Smimc: Axle loads
                    Smimct: Tandem axle loads
                    Smimcw: Wheel loads
                Smimd: Breaking loads
                Smimf: Concentrated loads
                Smimh: Dynamic loads
                    Smimhb: Blast loads
                Smimm: Live loads
                Smimr: Repeated loads
                Smims: Static loads
                Smimw: Load transfer
            Smip: Pressure
                Smipa: Air pressure
                Smipb: Back pressure
                Smipc: Confining pressure
                    Smipcg: Ground pressure
                Smipd: Dynamic pressure
                Smipe: Earth pressure
                    Smipes: Soil structure interaction
                Smipg: Effective stress
                Smipp: Pore pressure
                    Smippr: Pore water pressures
                    Smipps: Soil suction
                Smipq: Preconsolidation pressure
                Smips: Static pressure
                Smipu: Uplift pressure
                Smipv: Vacuum
                Smipw: Water pressure
                    Smipwd: Hydrodynamic pressure
                    Smipws: Hydrostatic pressure
                Smipx: Wind pressure
            Smir: Propulsion
            Smis: Pumping (Pavements)
            Smit: Set forward force
            Smiu: Tractive forces
        Smk: Gravitation
            Smke: Gravitational force
            Smkg: Gravity
                Smkgc: Center of gravity
        Smp: Momentum
        Sms: Stability (Mechanics)
            Smsd: Directional stability
            Smsf: Dynamic stability
        Smu: Statics
            Smub: Adhesion
            Smue: Aerostatics
                Smuep: Pneumatics
            Smuf: Equilibrium (Mechanics)
            Smuh: Hydrostatics
            Smum: Moments (Mechanics)
                Smumm: Moments of inertia
                Smumr: Resisting moments
        Smv: Stresses
            Smvb: Arching (Soils)
            Smvc: Biaxial stress
            Smvd: Deviatoric stress
            Smvj: Inelastic stress
            Smvp: Principal stresses
            Smvq: Residual stress
            Smvr: Reynolds stress
            Smvs: Shear stress
            Smvu: Uniaxial stress
            Smvy: Yield stress
        Smw: Waves
            Smwe: Elastic waves
            Smwg: Gravity waves
            Smwk: Internal waves
            Smwm: Longitudinal waves
            Smwn: Plane waves
            Smwo: Solitons
            Smwp: Surges (Fluid mechanics)
            Smws: S waves
            Smwy: Wave motion
    So: Light
        Sob: Becke line
        Sod: Distortion (Optics)
        Soe: Flicker
        Sof: Fluorescence
        Soh: Glare
        Soj: Infrared radiation
        Sok: Laser beams
        Som: Light transmission
            Somd: Diffusion (Optics)
            Soms: Light scattering
            Somu: Luminescence
                Somuc: Chemiluminescence
        Son: Photovoltaic effect
        Sop: Polarized light
        Sos: Solar radiation
            Sose: Solar energy
            Soss: Sunlight
        Sou: Ultraviolet radiation
    Sp: Nuclear phenomena
        Spc: Electromagnetic pulses
        Spd: Excitation
        Spe: Nuclear energy
            Spep: Nuclear power
        Spf: Nuclear explosions
        Spg: Nuclear magnetic resonance
        Spm: Nuclear radiation
            Spmb: Alpha rays
            Spme: Beta rays
            Spmg: Gamma rays
            Spmj: Ionizing radiation
                Spmjj: Irradiation
        Sps: Nuclear reactions
            Spsc: Fission
            Spsk: Fusion
            Spsr: Spallation
            Spsu: Transfer reactions
        Spu: Radioactivity
    Sr: Surface phenomena
        Srb: Boundary layer
            Srbj: Interfaces
                Srbjc: Air water interfaces
                Srbjp: Oil water interfaces
                Srbjs: Surfaces
                    Srbjsh: Holes
            Srbt: Turbulent boundary layer
        Src: Capillarity
        Srf: Rayleigh waves
        Srh: Sorption
            Srhd: Absorption
                Srhde: Energy absorption
            Srhk: Adsorption
            Srhr: Desorption
        Srm: Surface dynamics
        Srp: Surface energy
            Srpb: Absorption spectra
        Srr: Surface tension
        Srv: Volume changes
            Srvb: Compression
                Srvbb: Axial compression
                Srvbc: Decompression
            Srvc: Consolidation
                Srvcp: Overconsolidation
                Srvcs: Secondary consolidation
            Srvg: Expansion
                Srvgs: Dilation
                Srvgt: Thermal expansion
            Srvk: Contraction
                Srvks: Shrinkage
            Srvr: Swelling
    St: Heat
        Stb: Heat balance
        Stc: Heat conduction
        Std: Heat convection
        Ste: Heat cycle
        Stf: Heat exchange
        Stg: Heat flow
        Sth: Heat flux
        Stj: Heat loss
            Stjs: Scaling factor
        Stk: Heat radiation
            Stke: Emissivity
        Stm: Heat transfer
        Stn: Latent heat
        Sto: Phase equilibrium
        Stp: Phase transitions
            Stpb: Boiling
            Stpc: Condensation
            Stpd: Contraction (Thermodynamics)
            Stpe: Evaporation
            Stpf: Freezing
            Stpk: Liquefaction
            Stpm: Melting
            Stps: Solidification
            Stpu: Vapor phases
            Stpv: Volatilization
                Stpvb: Boil off
        Stq: Supercooling
        Str: Temperature gradients
            Strt: Thermoclines
        Sts: Degradation (Thermodynamics)
        Stt: Thermal diffusion
        Stu: Thermal efficiency
        Stv: Thermal expansion
        Stw: Thermal fatigue
        Stx: Thermal stresses
            Stxs: Thermal shock
        Sty: Vapor pressure
    Sy: Systems
        Sya: System architecture
        Syc: Complex systems
        Sye: Discrete systems
        Syg: Fuzzy systems
        Syn: Networks
            Synk: Links (Networks)
            Synn: Nodes (Networks)
        Sys: Subsystems
T: Disciplines
    Tb: Interdisciplinary studies
    Tc: Humanities
        Tcb: Art
        Tch: History
        Tcm: Music
        Tcp: Philosophy
            Tcpb: Aesthetics
    Tg: Social sciences
        Tgc: Anthropology
            Tgcp: Anthropometry
        Tgf: Archaeology
        Tgh: Business administration
        Tgj: Criminology
        Tgm: Economics
            Tgmb: Agricultural economics
            Tgmc: Econometrics
            Tgmj: Industrial economics
            Tgmm: Macroeconomics
            Tgmr: Microeconomics
            Tgmt: Regional economics
            Tgmw: Welfare economics
        Tgn: International relations
        Tgp: Education
        Tgr: Law
        Tgt: Political science
        Tgv: Psychology
            Tgvp: Psychometrics
            Tgvr: Psychophysics
            Tgvs: Social psychology
        Tgx: Sociology
            Tgxs: Sociometrics
    Tp: Science
        Tpb: Astronomy
        Tpd: Biology
            Tpdb: Biophysics
                Tpdbb: Bioacoustics
                Tpdbd: Biodynamics
                Tpdbk: Biokinematics
            Tpde: Botany
            Tpdg: Ecology
                Tpdgm: Limnology
                Tpdgr: Restoration ecology
            Tpdj: Genetics
                Tpdjb: Biotechnology
            Tpdm: Marine biology
            Tpdp: Microbiology
            Tpdr: Morphology
                Tpdrb: Anatomy
            Tpdt: Physiology
                Tpdte: Electrophysiology
            Tpdv: Systematics
                Tpdvt: Taxonomy
            Tpdx: Zoology
        Tph: Chemistry
            Tphb: Analytical chemistry
                Tphbc: Chromatography
            Tphe: Biochemistry
            Tphj: Inorganic chemistry
                Tphjm: Mineralogy
            Tphp: Organic chemistry
            Tphs: Pharmacology
                Tphst: Toxicology
            Tphx: Physical chemistry
                Tphxe: Electrochemistry
                Tphxp: Photochemistry
                Tphxt: Thermochemistry
        Tpn: Earth sciences
            Tpnb: Geography
                Tpnbh: Hydrography
            Tpng: Geology
                Tpngb: Geochemistry
                    Tpngbs: Soil chemistry
                Tpngd: Geological oceanography
                Tpngf: Geomorphology
                Tpngj: Petrography
                Tpngn: Petroleum geology
                Tpngp: Petrology
                Tpngq: Soil science
                Tpngr: Stratigraphy
                Tpngu: Tectonics
            Tpnp: Geophysics
                Tpnpb: Atmospheric physics
                Tpnpg: Geodesy
                Tpnph: Hydrology
                    Tpnphh: Hydrogeology
                    Tpnphs: Snow mechanics
                Tpnpp: Oceanography
                    Tpnppb: Bathymetry
                Tpnps: Rock mechanics
                Tpnpu: Seismology
            Tpnt: Meteorology
                Tpntb: Anemometry
                Tpntc: Atmospheric chemistry
                Tpntd: Climatology
        Tpp: Environmental sciences
        Tpr: Mathematics
            Tprb: Algebra
            Tprc: Calculus (Mathematics)
            Tprg: Geometry
                Tprgp: Plane geometry
            Tprm: Logic (Mathematics)
            Tprp: Operations research
            Tprs: Statistics
                Tprsb: Biometrics
                Tprsp: Probability theory
            Tprt: Time series analysis
            Tprv: Trigonometry
        Tpx: Physics
            Tpxc: Acoustics
                Tpxcs: Sonics
                    Tpxcsu: Ultrasonics
            Tpxe: Atomic physics
                Tpxen: Nuclear physics
            Tpxh: Classical field theory
            Tpxk: Cryogenics
            Tpxn: Crystallography
            Tpxq: Electromagnetism
                Tpxqe: Electrokinetics
                Tpxqm: Magnetohydrodynamics
            Tpxr: Electronics
                Tpxrs: Solid state electronics
            Tpxs: Mechanics
                Tpxsf: Fluid mechanics
                    Tpxsfb: Aeronautics
                    Tpxsfh: Hydraulics
                    Tpxsfk: Hydromechanics
                Tpxsk: Kinematics
                Tpxsr: Rheology
                Tpxst: Tribology
            Tpxt: Quantum mechanics
            Tpxu: Statistical mechanics
            Tpxv: Optics
                Tpxvj: Interferometry
                Tpxvm: Microscopy
                    Tpxvme: Electron microscopy
                Tpxvp: Photometry
            Tpxw: Spectroscopy
            Tpxy: Thermodynamics
    Tt: Technology
        Ttb: Agriculture
            Ttbf: Forestry
        Ttc: Appropriate technology
        Tte: Communications
            Ttec: Cybernetics
            Ttej: Information theory
        Ttg: Computer science
            Ttgj: Information technology
        Ttk: Engineering
            Ttkb: Aerospace engineering
                Ttkbb: Aeronautical engineering
                    Ttkbbb: Avionics
            Ttkc: Biomedical engineering
            Ttkd: Chemical engineering
            Ttkf: Civil engineering
                Ttkfb: Coastal engineering
                Ttkfd: Construction engineering
                Ttkff: Engineering geology
                Ttkfh: Foundation engineering
                Ttkfj: Geotechnical engineering
                    Ttkfjs: Soil mechanics
                Ttkfm: Municipal engineering
                Ttkfp: Sanitary engineering
                Ttkfr: Structural engineering
                    Ttkfrb: Bridge engineering
                    Ttkfre: Earthquake engineering
                Ttkft: Surveying
                Ttkfw: Transportation engineering
                    Ttkfwh: Highway engineering
                    Ttkfwr: Railroad engineering
                    Ttkfwt: Traffic engineering
            Ttkg: Design engineering
            Ttkh: Electrical engineering
                Ttkhm: Logic (Electricity)
            Ttki: Engineering mathematics
                Ttkib: Applied mechanics
                    Ttkibs: Structural mechanics
            Ttkj: Environmental engineering
            Ttkk: Human factors engineering
            Ttkm: Illuminating engineering
            Ttkn: Industrial engineering
                Ttknb: Concurrent engineering
                Ttknc: Cost engineering
                Ttkng: Engineering economy
                Ttknk: Ergonomics
                Ttknp: Management science
                Ttkns: Robotics
                Ttknv: Safety engineering
                Ttknx: Value engineering
            Ttkp: Materials science
                Ttkpm: Metallurgy
            Ttkq: Mechanical engineering
                Ttkqb: Automotive engineering
                Ttkqm: Mechatronics
            Ttkr: Military engineering
            Ttks: Mining engineering
            Ttkt: Naval architecture
                Ttktm: Marine engineering
            Ttku: Nuclear engineering
            Ttkv: Ocean engineering
            Ttkw: Petroleum engineering
            Ttky: Systems engineering
        Ttn: Environmental design
            Ttnb: Architecture
            Ttnd: City planning
            Ttnm: Landscape architecture
        Ttq: Graphic arts
            Ttqc: Cartography
            Ttqg: Cinematography
            Ttqp: Photogrammetry
            Ttqs: Photography
        Ttu: Medicine
            Ttud: Epidemiology
            Ttuf: Etiology
            Ttuh: Forensic medicine
            Ttum: Neurology
            Ttup: Pathology
            Ttuq: Psychiatry
            Ttus: Public health
            Ttux: Transportation medicine
                Ttuxb: Automotive medicine
                Ttuxd: Aviation medicine
        Ttx: Nucleonics
            Ttxh: Health physics
    Ty: Methodology
U: Mathematics
    Ub: General principles of mathematics
        Ubb: Mathematical methods
            Ubbp: Programming (Mathematics)
                Ubbpj: Integer programming
                    Ubbpjm: Mixed integer programming
                Ubbpm: Linear programming
                Ubbpp: Nonlinear programming
                    Ubbppd: Dynamic programming
                Ubbps: Stochastic programming
        Ubd: Logic (Mathematics)
            Ubdb: Boolean operators
            Ubdf: Fuzzy logic
            Ubds: Sets
                Ubdsc: Continuum (Mathematics)
                Ubdsf: Fuzzy sets
                Ubdsj: Invariants
                Ubdsm: Lattices (Mathematics)
            Ubdv: Variables
                Ubdvc: Complex variables
        Ube: Mathematical relations
            Ubee: Equations
                Ubeef: Formulas
                Ubeem: Linear equations
                Ubeep: Nonlinear equations
            Ubet: Transformations (Mathematics)
        Ubf: Approximation (Mathematics)
            Ubfb: Asymptotic expansion
            Ubfc: Curve fitting
            Ubff: Finite differences
            Ubfj: Interpolation
            Ubfk: Iterative methods
                Ubfkv: Validity
            Ubfm: Least squares method
            Ubfp: Numerical integration
            Ubfs: Splines
        Ubk: Combinatorial analysis
            Ubkp: Optimization
                Ubkpm: Maximization
                Ubkpp: Minimization
                Ubkps: Simulated annealing
                Ubkpt: Tabu search
        Ubm: Mathematical models
            Ubme: Econometric models
            Ubmg: Algorithms
                Ubmgb: Branch and bound algorithms
                Ubmgc: Computer algorithms
                    Ubmgce: Expert systems
                        Ubmgcek: Knowledge acquisition (Expert systems)
                Ubmgf: Fuzzy algorithms
                Ubmgg: Genetic algorithms
                Ubmgq: Shortest path algorithms
                Ubmgs: Simplex method
                Ubmgu: Progression (Mathematics)
            Ubmk: Automata theory
                Ubmkf: Finite automata
                    Ubmkfc: Cellular automata
            Ubms: Simulation
                Ubmsb: Analog simulation
                Ubmsd: Digital simulation
                Ubmsf: Hardware in the loop simulation
                Ubmsh: Hybrid simulation
                Ubmsm: Microsimulation
                Ubmsv: Virtual reality
        Ubt: Theorems
            Ubtp: Proof
            Ubtt: Theory
    Ud: Algebra and number theory
        Udc: Number theory
        Udf: Algebra
            Udfb: Algebraic operations
                Udfbe: Exponential functions
                Udfbf: Logarithms
                    Udfbfm: Modulus
                Udfbp: Ratios
                    Udfbpp: Proportion
                Udfbq: Dimensionless parameters
            Udfe: Theory of equations
                Udfeb: Boolean algebra
                Udfed: Linear algebra
                    Udfedd: Determinants (Mathematics)
                    Udfede: Eigenvalues
                    Udfedm: Matrices (Mathematics)
                Udfem: Multinomials
                Udfep: Polynomials
                    Udfepd: Discriminant analysis
                    Udfepq: Quadratic equations
                Udfes: Simultaneous equations
    Uf: Arithmetic
        Ufb: Arithmetic operations
            Ufbf: Fractions
            Ufbp: Percent
        Ufd: Calculation
            Ufde: Error analysis
        Ufn: Numbers
    Uh: Mathematical analysis
        Uhb: General aspects of mathematical analysis
            Uhbc: Calculus
                Uhbcf: Fourier analysis
                Uhbcg: Fourier series
                Uhbct: Tensor analysis
                Uhbcv: Vector analysis
                    Uhbcvw: Eigenvectors
            Uhbd: Functions (Mathematics)
                Uhbdp: Oscillations (Mathematics)
            Uhbf: Functional analysis
                Uhbfh: Harmonic analysis (Mathematics)
                    Uhbfhw: Wavelets
                Uhbfk: Integral equations
                Uhbfm: Integrals
                    Uhbfmc: Calculus of variations
                        Uhbfmcv: Variational inequalities (Mathematics)
                Uhbfp: Potential theory
        Uhc: Operational calculus
            Uhct: Transforms (Integral operators)
                Uhctf: Fourier transforms
                    Uhctff: Fast Fourier transforms
                Uhcth: Hough transforms
                Uhctm: Laplace transforms
        Uhd: Differential equations
            Uhdb: Boundary value problems
                Uhdbb: Boolean functions
            Uhde: Dynamic models
                Uhdeg: Green's function
            Uhdk: Partial differential equations
                Uhdkh: Hyperbolic functions
            Uhdm: Linear differential equations
            Uhdn: Nonlinear differential equations
            Uhdp: Perturbation theory
                Uhdpp: Perturbations
        Uhm: Special functions (Mathematics)
            Uhmp: Lagrangian functions
        Uht: Numerical analysis
            Uhtb: Boundary element method
            Uhte: Extrapolation
        Uhv: Sensitivity analysis
        Uhw: Frequency domain analysis
        Uhx: Time domain analysis
        Uhy: Catastrophe theory
    Uk: Heuristic methods
    Un: Topology
        Ung: Graph theory
            Ungp: Petri nets
            Ungs: Traveling salesman problem
            Ungv: Trees (Mathematics)
        Uns: Structural stability (Mathematics)
    Up: Geometry
        Upb: Geometric configurations and shapes
            Upba: Circles
            Upbb: Cones
            Upbc: Cubes
            Upbd: Curvature
            Upbe: Curves (Geometry)
                Upber: Radials
                Upbes: Sine curves
            Upbf: Cylinders (Geometry)
                Upbfc: Circular cylinders (Geometry)
            Upbj: Fractals
            Upbp: Parabolas
            Upbr: Rectangles
            Upbs: Spheres
            Upbt: Spirals
            Upbu: Symmetry
                Upbub: Bodies of revolution
            Upbw: Triangles
        Upd: Geometric elements
            Upda: Area
            Updb: Axis
            Updg: Diameter
            Updj: Height
                Updjb: Altitude
            Updo: Orthogonality
            Updp: Points (Geometry)
                Updpe: Ellipses
            Updr: Radius
            Updv: Secant
            Updw: Tangents
            Updx: Width
        Uph: Euclidean spaces
        Upq: Analytic geometries
            Upqe: Parametric equations
    Us: Statistical analysis
        Usa: Analysis of variance
            Usac: Covariance
            Usav: Variance
                Usavh: Heteroscedasticity
        Usb: Backcalculation
        Usd: Correlation analysis
            Usdb: Autocorrelation
            Usdc: Cross correlation
            Usds: Spatial analysis
        Use: Estimation theory
            Useb: Bias (Statistics)
            Usec: Choice models
                Usecm: Logits
                    Usecmm: Multinomial logits
                Usecp: Probits
                    Usecpm: Multinomial probits
            Usem: Maximum likelihood method
        Usf: Hypothesis testing
            Usfc: Chi square test
            Usfe: Critical values
        Ush: Mathematical prediction
            Ushd: Decision theory
                Ushdb: Bayes' theorem
                Ushde: Expected value
        Usi: Meta-analysis
        Usj: Multivariate analysis
            Usjb: Cluster analysis
            Usjd: Disaggregate analysis
            Usjf: Factor analysis
            Usjs: Structural equation modeling
        Usk: Nonparametric analysis
        Usm: Parametric analysis
        Usp: Probability
            Uspc: Confidence intervals
                Uspcc: Confidence coefficient
                Uspcm: Confidence limits
            Uspg: Game theory
            Uspj: Goodness of fit
            Uspm: Monte Carlo method
            Uspn: Personal probability
            Uspp: Probability density functions
            Uspr: Random functions
        Usq: Randomization
        Usr: Ranking (Statistics)
            Usrs: Significance (Statistics)
        Uss: Regression analysis
            Ussm: Linear regression analysis
            Usso: Logistic regression analysis
            Ussr: Multiple regression analysis
        Ust: Reliability (Statistics)
        Usv: Sequential analysis
        Usw: Statistical sampling
            Uswc: Control groups
            Uswj: Statistical inference
            Uswr: Random sampling
                Uswrs: Standard error
            Uswt: Representative samples (Statistics)
            Uswv: Sufficiency (Statistics)
            Uswy: T test
        Usx: Stochastic processes
            Usxb: Branching processes
            Usxm: Markov processes
                Usxmc: Markov chains
            Usxq: Queuing theory
            Usxt: Random variables
        Usy: Descriptive statistics
            Usyb: Dispersion (Statistics)
            Usyd: Distributions (Statistics)
                Usydb: Beta distributions
                Usydd: Binomial distributions
                Usydf: Chi square distributions
                Usydj: Delta functions
                Usydk: Exponential distributions
                Usydl: Frequency distributions
                    Usydlk: Kurtosis
                Usydn: Gamma distributions
                Usydp: Geometric distributions
                Usydr: Normal distributions
                Usydt: Poisson distributions
                Usydv: Skewed distributions
                Usydx: Weibull distributions
            Usyf: Factors (Statistics)
                Usyfc: Coefficients
            Usyg: Measures of central tendency
                Usygb: Average
                Usygg: Mean (Statistics)
            Usyh: Deviation (Statistics)
                Usyhs: Standard deviation
            Usyr: Range (Statistics)
            Usyt: Time series
            Usyv: Trend (Statistics)
V: Areas and regions
    Vc: Areas
        Vch: Hemispheres
            Vche: Eastern hemisphere
            Vchn: Northern hemisphere
            Vchs: Southern hemisphere
            Vchw: Western hemisphere
        Vck: Continents
            Vckc: Continental shelf
        Vcr: Climatic regions
            Vcrf: Frigid regions
                Vcrfp: Polar regions
                Vcrft: Tundra
            Vcrm: Temperate regions
            Vcrs: Subtropics
            Vcrt: Tropics
    Vg: Land areas
        Vga: General surface features of the earth
            Vgap: Terrain
            Vgat: Topography
        Vgc: Grasslands
        Vgd: Arid land
            Vgdd: Deserts
        Vge: Forests
        Vgf: Plains
            Vgfc: Cliffs
            Vgff: Flood plains
            Vgfh: Hills
                Vgfhs: Slopes
                    Vgfhsr: Risers (Geology)
                    Vgfhss: Rock slopes
                    Vgfhst: Talus slopes
            Vgfr: River basins
            Vgfv: Valleys
        Vgh: Mountains
            Vghp: Passes (Mountains)
            Vghv: Volcanoes
        Vgi: Islands
        Vgk: Capes
        Vgp: Peninsulas
    Vh: Caverns
        Vhg: Galleries
    Vm: Land water marginal areas
        Vmb: Littoral
            Vmbb: Beaches
            Vmbd: Coasts
                Vmbdb: Bights
                Vmbdw: Waterfronts
        Vmd: Deltas
        Vmf: Wetlands
        Vmj: Bogs
        Vmm: Marshes
        Vmr: Reefs
        Vms: Swamps
        Vmw: Watersheds
    Vs: Water areas
        Vsb: Aquifers
        Vse: Open water
        Vsj: Fresh surface water features
            Vsjc: Backwaters
            Vsjf: Rivers
                Vsjfs: Streams
                    Vsjfsc: Canyons
                    Vsjfsf: Fords (Hydrology)
                    Vsjfsg: Gullies
                    Vsjfsm: Meanders
            Vsjp: Lakes
                Vsjpm: Lagoons
        Vss: Salt water areas
            Vssb: Oceans
                Vssbb: Ocean bottom
            Vssg: Seas
                Vssgt: Territorial seas
            Vssi: Bays
            Vsss: Estuaries
    Vv: Areas by point of view
        Vvd: Domestic
        Vvf: Foreign
        Vvi: International
            Vvib: Binational
            Vvid: International borders
                Vvidr: Border regions
    Vw: Socioeconomic areas
        Vwa: Countries
            Vwab: Developed countries
            Vwad: Developing countries
        Vwb: States
        Vwc: Counties
        Vwq: Regions
            Vwqm: Metropolitan areas
        Vwr: Rural areas
        Vwu: Urban areas
            Vwub: Business districts
                Vwubc: Central business districts
                Vwube: Business parks
            Vwuc: Cities and towns
                Vwucc: Cities
                    Vwuccs: Small cities
                    Vwuccu: Medium sized cities
                    Vwuccx: Large cities
                Vwucs: Suburbs
                Vwuct: Towns
                    Vwuctn: New towns
                    Vwucts: Small towns
        Vwv: Residential areas
            Vwvn: Neighborhoods
            Vwvs: Subdivisions
        Vww: Communities
        Vwx: Industrial areas
            Vwxb: Brownfields
        Vwy: Workplaces
    Vx: Wilderness areas
W: Time
    Wc: Chronological time
    We: Time periods
        Wea: Centuries
            Weab: 15th century
            Weac: 16th century
            Wead: 17th century
            Weae: 18th century
            Weaf: 19th century
            Weag: 20th century
            Weah: 21st century
        Web: Seasons
            Webd: Spring
            Webe: Summer
            Webf: Fall
            Webg: Winter
        Weg: Periods of the day
            Wegd: Dawn
            Wegf: Daylight
            Wegh: Twilight
                Weghd: Dusk
            Wegj: Darkness
            Wegm: Morning
            Wegn: Afternoon
            Wego: Evening
            Wegp: Night
        Wep: Peak periods
        Weq: Off peak periods
    Wg: Time duration
        Wgj: Years
        Wgm: Months
        Wgn: Weeks
        Wgp: Days
            Wgpd: Weekdays
            Wgpe: Weekends
            Wgph: Holidays
            Wgpv: Anniversaries
        Wgq: Hours
    Wi: Time intervals
        Wif: Quinquennial
        Wig: Biennial
        Wik: Annual
            Wikh: Semiannual
            Wikq: Quarterly
            Wiks: Bimonthly
        Wim: Monthly
        Win: Weekly
        Wip: Daily
        Wiq: Hourly
    Wq: Time alteration
        Wqd: Daylight saving time
        Wqt: Time zones
    Wr: Relative time
        Wrd: Past
        Wre: Present
        Wrf: Future
        Wrg: Time lag
        Wrl: Lead time
        Wrm: Running time
        Wrw: Time dependence
X: Information organization
    Xb: Information management
        Xbb: Guides to information
            Xbbc: Classification
                Xbbcc: Coding systems
                    Xbbccd: Document markup languages
                        Xbbccdh: HTML (Document markup language)
                        Xbbccdx: XML (Document markup language)
                    Xbbccj: Image coding
                    Xbbcck: Color codes
            Xbbf: Indexes (Information management)
            Xbbk: Catalogs
            Xbbm: Guides to the literature
            Xbbq: Bibliographies
            Xbbw: Biographies
            Xbbx: Abstracts
            Xbby: Syntheses
        Xbd: Library operations
            Xbdc: Collection development
            Xbdm: Cataloging
                Xbdmj: Indexing
            Xbdr: Document delivery
        Xbf: Information systems
            Xbfd: Decision support systems
                Xbfdd: Decision trees
            Xbfg: Geographic information systems
            Xbfm: Management information systems
            Xbfr: Real time information
        Xbk: Data processing
            Xbkc: Data collection
                Xbkcb: Automatic data collection systems
            Xbkd: Data processing operations
                Xbkdb: Artificial intelligence
                    Xbkdbc: Backpropagation
                    Xbkdbe: Case based reasoning
                    Xbkdbj: Intelligent agents
                    Xbkdbm: Learning (Artificial intelligence)
                Xbkdc: Data reduction
                Xbkdd: Data fusion
                Xbkde: Data logging
                Xbkdf: Distributed processing
                    Xbkdfc: Client server computing
                    Xbkdfm: Middleware
                    Xbkdfp: Pipeline processing
                Xbkdg: Data compression
                Xbkdh: Fault tolerant computing
                Xbkdi: Data mining
                Xbkdj: Mobile computing
                Xbkdm: Multitasking
                Xbkdn: Neural networks
                Xbkdp: Parallel processing
                Xbkdr: Real time data processing
                Xbkds: Soft computing
            Xbke: Data entry
            Xbkg: Data files
                Xbkgd: Databases
                    Xbkgdd: Data banks
                    Xbkgdf: Distributed databases
                    Xbkgdo: Object oriented databases
                    Xbkgdr: Relational databases
                    Xbkgdw: Data warehouses
                    Xbkgdy: Database management systems
                        Xbkgdyd: Data dictionaries
                        Xbkgdym: Metadata
                Xbkgp: Data protection
                Xbkgq: Data quality
            Xbkj: Software
                Xbkjb: Computer operating systems
                Xbkjc: Computer programs
                    Xbkjcp: Spreadsheets
                    Xbkjcs: Subroutines
                Xbkjj: Interactive computer systems
                Xbkjm: Multi-agent systems
                Xbkjs: Software packages
            Xbkm: Computer programming
                Xbkmd: Computer programming languages
                Xbkmm: Programming manuals
                Xbkmq: Software maintenance
                    Xbkmqc: Configuration management
                    Xbkmqx: Year 2000 date conversion
                Xbkms: Computer program documentation
                Xbkmu: Object oriented programming
            Xbkn: Information storage and retrieval systems
                Xbknd: Data storage
                    Xbkndf: Formatting
                Xbknj: Information retrieval
                    Xbknjh: Hypertext
                        Xbknjhw: Websites (Information retrieval)
                            Xbknjhwh: Home pages (Websites)
            Xbko: Computer network resources
            Xbkp: Computer output
                Xbkpb: Computer printouts
                Xbkpg: Computer graphics
                    Xbkpgc: Computer animation
                    Xbkpgv: Visualization
                Xbkpm: Computer models
            Xbkr: Computer networks
                Xbkrb: Computer architecture
                    Xbkrbp: Open systems architecture
                Xbkrd: Internetworking (Telecommunication)
                Xbkrf: Computer network protocols
                    Xbkrfe: Ethernet
                Xbkrj: Internet
                Xbkrk: Intranet
                Xbkrm: Local area networks
                    Xbkrmw: Wireless LANs
                Xbkrw: Wide area networks
            Xbks: Computer security
                Xbksv: Computer viruses
    Xk: Activities leading to information generation
        Xkb: Research
            Xkbr: Research projects
                Xkbrd: Demonstration projects
            Xkby: Scientific method
                Xkbyc: Problem solving
                Xkbyf: Problem identification
        Xkd: Studies
            Xkdb: Before and after studies
            Xkdc: Case studies
                Xkdcm: Longitudinal studies
            Xkde: Cross sectional studies
            Xkdf: Field studies
            Xkdg: Laboratory studies
            Xkdi: Impact studies
                Xkdie: Environmental impact statements
            Xkdk: Panel studies
            Xkdl: Pilot studies
            Xkdn: State of the art studies
            Xkdr: Study tours
            Xkdt: Theoretical studies
            Xkdw: Time studies
        Xkf: Surveys
            Xkfq: Questionnaires
        Xkh: Hearings
            Xkhk: Congressional hearings
        Xkm: Meetings
            Xkmj: Interviewing
        Xkp: Conferences
        Xkv: Lectures
        Xkw: Workshops
        Xky: Reconnaissance
            Xkyc: Aerial reconnaissance
    Xs: Information dissemination
        Xsd: Data sharing
        Xsj: Information services
        Xsn: News
        Xsq: Technical assistance
        Xst: Technology transfer
    Xx: Documents
        Xxb: Monographs
            Xxbb: Brochures
            Xxbf: Directories
            Xxbg: Guidelines
            Xxbh: Manuals
                Xxbhh: Handbooks
            Xxbr: Reprints
            Xxbt: Theses
            Xxby: Textbooks
        Xxf: Serials
            Xxff: Periodicals
                Xxffe: Ephemerides
            Xxfn: Newspapers
        Xxk: Dictionaries
            Xxkd: Definitions
            Xxke: Encyclopedias
            Xxkg: Glossaries
        Xxl: Registers
        Xxm: Correspondence
        Xxp: Patents
            Xxpa: Patent applications
        Xxq: Reviews
            Xxqa: Annual reviews
            Xxqm: Literature reviews
        Xxr: Reports
            Xxra: Annual reports
            Xxrr: Research reports
            Xxrs: State of the art reports
            Xxrt: Technical reports
            Xxrv: Reports of visits
        Xxs: Specifications
            Xxsp: Performance based specifications
            Xxss: Standards
        Xxt: Tables (Data)
        Xxu: Forms (Documents)
        Xxv: Visual presentations
            Xxve: Pictures
                Xxved: Drawings
                    Xxvedp: Perspective views
                    Xxvedr: Plans (Drawings)
                    Xxvedt: Technical drawings
                Xxvep: Photographs
                    Xxvepe: Electron micrographs
                    Xxvepo: Orthophotographs
                    Xxveps: Stereoscopic models
            Xxvg: Graphs
            Xxvh: Diagrams
                Xxvhb: Contours
                Xxvhc: Cross sections
                Xxvhf: Flow charts
                Xxvhh: Flow net
                Xxvhk: Histograms
            Xxvm: Maps
                Xxvmc: Charts
                    Xxvmcp: Design charts
                    Xxvmcs: Nomographs
                    Xxvmcu: Organization charts
                Xxvmk: Contour maps
                Xxvmm: Digital maps
                Xxvmt: Topographic maps
                Xxvmy: Atlases
        Xxw: Multimedia
            Xxwa: Audiovisual aids
            Xxwv: Visual aids
        Xxx: Translations
        Xxy: Legal documents
            Xxyt: Testimony
    Xy: Physical media (Information management)
        Xyb: Print on paper documents
        Xyd: Microforms
        Xyh: Audio media
            Xyht: Audio tapes
        Xyk: Visual media
            Xykm: Motion pictures
            Xykp: Film
                Xykpc: Color film
        Xym: Electronic media
            Xymc: Punched cards
            Xymd: Floppy disks
            Xymr: CD-ROM
            Xyms: DVDs
            Xymt: Magnetic tapes
                Xymtv: Videotapes