IMDATA4.TXT
                           -----------
           Read Me file for IMDATA4.D I/M credit file
           ------------------------------------------

The file IMDATA4.D contains all of the I/M credits contained in the 
IMDATA3.D credit file released with the "hybrid" version of MOBILE5 
(MOB5A_H) with the addition of I/M credits for ASM test procedures 
based a combination of the data from the California El Monte Study and
the EPA testing in Phoenix, Arizona.

These credits can be accessed using MOBILE5 by selecting the following
parameters in the I/M Program Descriptive Record:


     Test Type = "3", Loaded/Idle Test (using MOBILE5a) or
               = "5", ASM Test (using MOBILE5b)
     Frequency = "1" or "2", Annual or Biennial
     
     Cutpoints =  HC    CO    NOx
                 ----  ----   ----
                  25.   50.    1.     Two Mode 2525/5015 ASM
                                      (Final ASM Standards)
                  25.   50.    2.     Two Mode 2525/5015 ASM
                                      (Start Up ASM Standards)
                  25.   25.    1.     Single Mode 2525 ASM
                                      (Final ASM Standards)
                  50.   15.    1.     Single Mode 5015 ASM
                                      (Final ASM Standards)
                  25.   25.    2.     Single Mode 2525 ASM
                                      (Start Up ASM Standards)
                  50.   15.    2.     Single Mode 5015 ASM
                                      (Start Up ASM Standards)

This dataset also contains the previously released versions of
ASM procedure I/M credits:

     Cutpoints =  HC    CO    NOx
                 ----  ----   ----
                  0.4   8.0    1.8    EPA Four Mode ASM (AZ Data)
                  
                  0.8   15.    2.0    Two Mode ASM Matching
                                      0.8/15/2.0 IM240 Failure Rate
                                      
                  1.2   20.    3.0    Two Mode ASM Matching
                                      1.2/20/3.0 IM240 Failure Rate
                                                        
                  
The file IMDATA4H.D contains all of the I/M credits contained in the 
HYBRID.IMC credit file released with the "hybrid" version of MOBILE5 
(MOB5A_H) with the addition of I/M credits for ASM test procedures. 
These credits can be accessed using the same parameters described above, 
but specifying the IMDATA4H.D file.

Section 2.2.5 of the MOBILE5 User Guide (regarding Inspection and 
Maintenance Programs) describes how to use alternate I/M credit
data files with the MOBILE5 model.