Library of Congress >> MARC >> Authority >> Names and Terms  >> X50

X50 - Topical Terms-General Information


MARC 21 Authority
October 2014

"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 Format for Authority Data that contains abridged descriptions of every data element, along with examples.


First Indicator Second Indicator
Undefined
# - Undefined

150/450/550 - Undefined
# - Undefined

750 - 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



Subfield Codes

Main term portion

  • $a - Topical term or geographic name entry element (NR)
  • $b - Topical term following geographic name entry element (NR)
  • $g - Miscellaneous information (R)

Tracing and linking subfields

  • $i - Relationship information (R)   [450/550/750]
  • $w - Control subfield (NR)   [450/550/750]
  • $0 - Authority record control number or standard number (R)   [550/750]
  • $2 - Source of heading or term (NR)   [750]
  • $4 - Relationship code (R)   [450/550/750]
  • $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)


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.

150 ##$aBlood
150 ##$aCatalogs by source
150 ##$aCharacters and characteristics in literature
150 ##$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.

450 ##$aWashington (D.C.)$bLincoln Memorial

$g - Miscellaneous information

Data element that is not more appropriately contained in another defined subfield.

150 ##$aUntergrund$gBodenkunde
150 ##$aUntergrund$gPolitik
[Examples in German of two different entities sharing the same word as their name]

$i - Relationship information   [450/550/750]

Designation of a relationship of the entity in a 450, 550, or 750 field to the 1XX entity in the record or a textual reference instruction phrase. For fields 450 and 550 the phrase may be system-generated from the field tag or from the codes defined for subfield $w (Control subfield). Subfield $i is appropriate only in fields 450, 550, and 750. Guidelines for using subfield $i in fields 450 and 550 are provided in the Tracings and References-General Information section. Guidelines for using subfield $i in field 750 are provided in the 7XX Heading Linking Entries-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.

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.

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.

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.

150 ##$aChapels$zGermany (West)
150 ##$aWater resources development$zKenya
150 ##$aMusic festivals$zIllinois

$0 - Authority record control number or standard number   [550/750]

See description of this subfield in Appendix A: Control Subfields.

$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.

$4 - Relationship code   [450/550/750]

Contains in coded form the designation of a relationship of the entity in a 450, 550, or 750 field to the 1XX entity in the record. Guidelines for using subfield $4 in fields 450 and 550 are provided in the Tracings and References-General Information section. Guidelines for using subfield $4 in field 750 are provided in the 7XX Heading Linking Entries-General Information section.

$5 - Institution to which field applies   [450/550/750]

See description of this subfield in Appendix A: Control Subfields.

$6 - Linkage

See description of this subfield in Appendix A: Control Subfields.

$8 - Field link and sequence number

See description of this subfield in Appendix A: Control Subfields.


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.

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.

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.

450 ##$aPh. D. degree

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.

 
Content designated field:
150 ##$aChapels$zGermany
Display example:
Chapels-Germany

CONTENT DESIGNATOR HISTORY

Indicator 2 - Nonfiling characters [150/450/550] [OBSOLETE, 1993]

Values were: 0-9 (Number of nonfiling characters present).

$g - Miscellaneous information [NEW, 2014]
$i - Reference instruction phrase [450/550] [REDEFINED, 2009]
$i - Relationship information [750] [NEW, 2014]
$v - Record control number [750] [REDEFINED, 1995] [USMARC only]
$0 - Record control number [550/750] [NEW, 1997]
$0 - Record control number [550/750] [REDEFINED, 2010]
$3 - Authority record control number [OBSOLETE, 1997] [CAN/MARC only]
$4 - Relationship code [450/550] [NEW, 2009]
$4 - Relationship code [750] [NEW, 2014]

Library of Congress >> MARC >> Authority >> Names and Terms  >> X50
(10/20/2014)
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