X50 - Topical Terms-General Information
MARC 21 Authority
October 2003
"Full" documentation refers to the MARC 21 Format for Authority Data that contains detailed descriptions of every data element, along with examples, input conventions and history sections.
"Concise" documentation refers to the MARC 21 Concise Format for Authority Data that contains abridged descriptions of every data element, along with examples.
450 - See From Tracing - Topical Term (R)
Full |
Concise
550 - See Also From Tracing - Topical Term (R)
Full |
Concise
750 - Established Heading Linking Entry - Topical Term (R)
Full |
Concise
First Indicator
Undefined
# - Undefined
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Second Indicator
150/450/550
-
Undefined
# - Undefined
750
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Thesaurus
0 - Library of Congress Subject Headings
1 - LC subject headings for children's literature
2 - Medical Subject Headings
3 - National Agricultural Library subject authority file
4 - Source not specified
5 - Canadian Subject Headings
6 - Répertoire de vedettes-matière
7 - Source specified in subfield $2 |
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Subfield Codes
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Main term portion
$a - Topical term or geographic name entry element (NR)
$b - Topical term following geographic name entry element (NR)
Tracing and linking subfields
$i - Reference instruction phrase (NR) [450/550]
$w - Control subfield (NR) [450/550/750]
$0 - Record control number (R) [550/750]
$2 - Source of heading or term (NR) [750]
$5 - Institution to which field applies (R) [450/550/750]
$6 - Linkage (NR)
$8 - Field link and sequence number (R)
| Subject subdivision portion
$v - Form subdivision (R)
$x - General subdivision (R)
$y - Chronological subdivision (R)
$z - Geographic subdivision (R)
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GUIDELINES FOR APPLYING CONTENT DESIGNATORS
Content designators identify the subelements occurring in topical term and node label
headings constructed according to generally accepted thesaurus-building conventions
(e.g., Library of Congress Subject Headings). Topical terms include occupation
and function terms that are used as the lead element of subject or added entry access
fields in bibliographic records. A topical term that is authorized for use
only as a subject subdivision part of an extended subject heading is
contained in a 180 (General Subdivision) or 182 (Chronological Subdivision) field.
Only generally-applicable content designators are described in full in this section. A
small number of content designators with field-specific instructions are described in
the Tracings and References-General Information section (for fields 450 and
550) and the 7XX Heading Linking Entries-General Information section (for field
750).
■ INDICATORS
First Indicator - Undefined Undefined and contains a blank (#).
Second Indicator In fields 150, 450, and 550, the second indicator position is undefined and
contains a blank (#). For field 750, the second indicator position contains one of
the values described in the
7XX Heading Linking Entries-General
Information section.
■ SUBFIELD CODES
$a - Topical term or geographic name entry element Topical subject, a geographic name used as an entry element for a topical term, or
a node label term. Parenthetical qualifying information is not separately subfield
coded.
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| 150 |
##$aBlood |
| 150 |
##$aCatalogs by source |
| 150 |
##$aCharacters and characteristics in
literature
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| 150 |
##$aBull Run, 2nd Battle of, Va., 1862 |
| 450 |
##$aCaracas.$bBolívar Statue
[Example of a non-LCSH topical see from tracing.] |
$b - Topical term following geographic name entry element Topical term that is entered under a geographic name contained in subfield $a.
This construction is not commonly used in 150 or 550 heading fields; it may occur
in 450 See From Tracing fields.
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| 450 |
##$aWashington (D.C.)$bLincoln Memorial |
$i - Reference instruction phrase [450/550]Reference instruction phrase other than those that may be system generated from
the field tag or from the codes defined for subfield $w (Control subfield).
Subfield $i is appropriate only in field 450 and 550. Guidelines for applying
subfield $i are provided in the Tracings and References-General
Information section.
$v - Form subdivision Designates a specific kind or genre of material as defined by the thesaurus being
used. Subfield $v is appropriate in the X50 fields only when a form subject
subdivision is added to a main term to form an extended heading.
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| 150 |
##$aScuba diving$vPeriodicals |
$w - Control subfield [450/550/750]Codes in one or more character positions defined to control the display of
information and specify relationships, restrictions, and status. Subfield $w is
appropriate only in field 450, 550, and 750. Character position definitions and
guidelines for applying the codes defined for subfield $w in field 450 and 550 are
provided in the Tracings and References-General Information section.
Character position definitions and guidelines for field 750 are provided in the
7XX Heading Linking Entries-General Information section.
$x - General subdivision Subject subdivision that is not more appropriately contained in subfield $v (Form
subdivision), subfield $y (Chronological subdivision), and subfield $z (Geographic
subdivision). Subfield $x is appropriate in the X50 fields only when a general
topical subject subdivision is added to a main term to form an extended
heading.
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| 150 |
##$aConflict of laws$xSupport (Domestic relations) |
| 150 |
##$aExecutives$xSalaries, etc. |
| 150 |
##$aAmusements$xReligious aspects$xBuddhism, [Christianity, etc.] |
$y - Chronological subdivision Subject subdivision that represents a period of time. Subfield $y is appropriate
in the X50 fields only when a chronological subject subdivision is added to the
main term to form an extended heading.
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| 150 |
##$aArchitecture, Modern$y19th century |
| 150 |
##$aGod$xHistory of doctrines$yMiddle Ages, 600-1500 |
| 150 |
##$aMusic$y500-1400 |
| 150 |
##$aPainting, Chinese$ySung-Yüan dynasties, 960-1368$xSocieties, etc. |
$z - Geographic subdivision Appropriate in the X50 fields only when a geographic subject subdivision is added
to a main term to form an extended heading.
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| 150 |
##$aChapels$zGermany (West) |
| 150 |
##$aWater resources development$zKenya |
| 150 |
##$aMusic festivals$zIllinois |
$0 - Record control number [550/750]
$2 - Source of heading or term [750]Code that identifies the source of a heading or term when the second indicator
position contains value 7. Subfield $2 is appropriate only in field 750.
Guidelines for applying subfield $2 are provided in the
7XX Heading Linking
Entries—General Information section.
$5 - Institution to which field applies [450/550/750]
$8 - Field link and sequence number
INPUT CONVENTIONS
Ambiguous Headings - See Appendix D: Ambiguous Headings.
Punctuation - Punctuation of the subelements of a heading is generally dictated by subject heading
system/thesaurus rules. These input conventions clarify MARC punctuation practices. An
X50 field does not end with a mark of punctuation unless the field ends with an
abbreviation, an initialism, or data that ends with a mark of punctuation.
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| 150 |
##$aMagazine illustration |
| 150 |
##$aSeasonal variations (Economics) |
| 150 |
##$aEducation$zWashington (D.C.) |
| 150 |
##$aMuseums$zRussia (Federation) |
| 150 |
##$aArt, Chinese$yTo 221 B.C. |
| 150 |
##$aResearch libraries$zMexico$xSocieties, etc. |
Spacing - No spaces are used in initialisms, acronyms, or abbreviations.
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| 150 |
##$aC.O.D. shipments |
| 450 |
##$aB.A. degree |
One space is used between preceding and succeeding initials if an abbreviation consists
of more than a single letter.
Display Constant
| - |
[dash associated with the content of subfield $v, $x, $y, and $z] |
Dash (-) that precedes a subject subdivision in an extended subject heading is not
carried in the MARC record. It may be system generated as a display constant associated
with the content of subfield $v, $x, $y, and $z.
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Content designated field:
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| 150 |
##$aChapels$zGermany
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Display example:
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Chapels-Germany
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CONTENT DESIGNATOR HISTORY
Indicator 2 - Nonfiling characters [150/450/550] [OBSOLETE, 1993]
Values were: 0-9 (Number of nonfiling characters present).
$v - Record control number [750] [REDEFINED, 1995] [USMARC only]
$0 - Record control number [550/750] [NEW, 1997]
$3 - Authority record control number [OBSOLETE, 1997] [CAN/MARC only]