Fixed field elements and variable fields
See MARC 21 Format for Authority Data for detailed descriptions of every data element, along with examples, input conventions, and history sections, used in LC/NACO name authority records and LC subject authority records. To browse and view authority headings for Subject, Name, Title, and Name/Title combinations, see Library of Congress Authorities.
Fixed field element definitions
The following table lists the fixed field elements and the codes for each element. The elements are listed in alphabetical order. Only codes typically used in LC/NACO name authority records and LC subject authority records are listed.
|Code||Name or description||Comments|
|Authority Record Number||OCLC system-supplied|
|Kind of record code||Indicates whether the record is an authority record (1xx is an established heading) or a reference record (1xx is not an established heading)|
|Level of establishment code||Indicates the status of a heading in an authority record|
|a||Fully established heading|
(established but not yet used)
(not an established heading)
|Encoding level||Indicates whether the authority record is complete|
|n||Complete authority record|
|o||Incomplete authority record|
|Date entered on file
Year, month, day
|Date record was entered|
|Direct/indirect geographic subdivision code||Indicates whether the 1xx heading can be subdivided geographically|
|Not subdivided geographically|
|Type of government agency code||If the heading is the name of a body created or controlled by a government, a one-character code denotes the jurisdictional level of the body. LC always uses a fill character (▮).|
|Not a government agency|
|a||Autonomous or semi-autonomous component of Malaysia|
|s||State, provincial, territorial, dependent, etc.|
|o||Government agency-type undetermined|
|u||Unknown if heading is for government agency|
|▮||No attempt to code|
|Modified record code||Shows whether the machine-readable authority record differs from the manual authority record|
|Record not modified|
|Undiffentiated personal name code||Indicates whether, because neither date nor distinguishing terms are available, the same heading is used for more than one person|
|a||Differentiated personal name|
|b||Undifferentiated personal name|
|Heading use code-main or added entry||Represents the author aspect of the heading|
|a||Heading appropriate for main or added entry|
|b||Heading not appropriate for main or added entry|
|Record status||Indicates relationship of record to a file for file maintenance purposes|
|c||Corrected or revised|
|Reference evaluation code||Indicates whether references have been evaluated and whether those references are consistent with the heading. Code b is used when the AACR2 or RDA form appears as the established heading (1xx) but the references may not have been re-evaluated in their relationships to the new heading.|
|a||Tracings are consistent with heading|
|b||Tracings are not necessarily consistent with heading|
|Date and time of latest transaction (NR)
|Date and time the record was last updated in the OCLC authority file (displayed in ‡a)|
|Romanization scheme||Indicates the Romanization scheme used in formulating the heading in the 1xx field.|
|c||Converted to Pinyin|
|n||Not converted to Pinyin|
|▮||No attempt to code|
|Descriptive cataloging rules code||Represents the cataloging rules used for establishing the name, name/title, or uniform title heading in the 1xx field. For newly created name/series authority records code "z" is the only value used. When existing NARs using codes "a", "b", "c", or "d" are modified in any way, they are re-coded to RDA and the 008/10 code is changed accordingly. Exceptions to this guideline are found in the Descriptive Cataloging Manual Z1 008/10 section. Do not use codes: a, b, d, or the fill character. LC uses code n (Not applicable) in traced reference records (008/09, code c).|
|d||AACR2 compatible heading|
|Numbered/unnumbered series code||Indicates whether a series is numbered, unnumbered, or varies between the two. The code used reflects the series as a whole; if numbering varies, variations are explained in field 640 and/or 641.|
|Heading use code-series added entry||Represents the series aspect of the heading|
|a||Heading appropriate as series added entry|
|b||Heading not appropriate as series added entry|
|Type of series code||Indicates which type of series the heading in the 1xx field represents, if any|
|Cataloging source code||Indicates the source of the authority data. Code c is used in records contributed through NACO to LC.|
|National bibliographic agency|
|c||Cooperative cataloging program|
|Type of subject subdivision||LC uses only n or a fill character to code this position.|
|Subject heading system/thesaurus code||Indicates the subject heading system used in establishing the heading. Code a routinely appears not only for special subject headings but also for names and uniform title headings valid for use in subject work as LC-established forms.|
|a||Library of Congress subject headings|
|b||LC subject headings for children's literature|
|Heading use code-subject added entry||Represents the subject aspect of the heading|
|a||Heading appropriate as subject added entry|
|b||Heading not appropriate as subject added entry|
|Type of record||Indicates the characteristics of and defines the components of the record|
|Record update in process code||Indicates whether a change in any field of the record is underway|
|a||Record can be used|
|b||Record is being updated|
Each variable field may have between 1 and 9,999 characters. Variable fields have three parts:
- Three-digit codes called tags
- Two single-digit indicators
- One or more subfields
The system groups variable fields by MARC 21 tags. Tags that begin with the same digit have similar functions. In the following list, xx stands for any numeric value (00-99).
- Tag groups and functions - Table
Tag group Function 0xx Control numbers, call numbers, coded data 1xx Established headings 260 Complex see reference (subject) 360 Complex see also reference (subject) 4xx See from reference 5xx See also from reference 6xx Series treatment information, notes, source citations 7xx Heading linking entries 856 Electronic location and access 9xx Locally defined headings
Indicators supply data for indexing and other system functions. Numbers in the indicator positions have assigned meanings, and in some fields blank () is meaningful. Variable field indicators may have the following combinations:
- A number in both positions
- A number in one position and a blank space in the other
- Two blank spaces
Subfields are the smallest logical unit of data in a variable field. Subfield codes (letters or numbers) identify subfields and are preceded by subfield delimiters (‡). Subfields usually have textual descriptions of the authority information, but some contain coded information.
Whenever subfield ‡a is the first subfield, both the delimiter and subfield code are implicit and do not display.
Control subfield ‡w
Subfield ‡w appears only in applicable 4xx, 5xx, and 7xx fields.
4xx and 5xx fields
Control subfield ‡w in the 4xx and 5xx fields contains four character positions (designated as ‡w/0, ‡w/1, etc.). It provides information about a specific relationship between a tracing (4xx or 5xx field) and a heading (1xx field).
- Use ‡w to indicate whether special instructions apply to the display of the reference in the 4xx or 5xx field.
- Use ‡w to indicate whether a tracing is restricted to the reference structure of a particular type of authority.
- Each character position has a list of coded values that pertain to it. See the following table.
The code definitions are position-dependent. If you code any of the character positions ‡w/1-‡w3 with a meaningful value (i.e., a value other than n (not applicable)), you must code all the preceding positions with n as a placeholder. Succeeding positions need not be coded. If all four positions contain n, subfield ‡w does not appear.
► 400 10 Sayers, Dorothy Leigh, ‡d 1893-1957 ‡w nna
The first two positions are coded n because the third position requires code a. The field contains a form of Sayers' name established under earlier cataloging rules. No code is needed in the fourth position because it does not apply to this tracing.
- 4xx and 5xx character positions - Table
Position Code Description 0
- Specifies the relationship between the tracing and the heading
a Earlier heading b Later heading d Acronym (pre-1981 records only) f Musical composition (pre-1981 records only) g Broader term n Not applicable r Relationship designation in subfield ‡i or ‡4 (valid in fields 500, 510, 511, and 530 only) 1
Tracing Use Restriction
- Indicates the authority reference structure in which the tracing is appropriate.
n Not applicable 2
Earlier Form of Heading
- Indicates whether the 4xx field is an earlier form of the heading established in the relevant national authority file or in an authority file other than the national authority file.
a Pre-AACR2 form of heading (national name authority file) e Earlier established form of heading (national authority file) n Not applicable 3
- Enables the generation of suppression of a cross reference from a 4xx or 5xx tracing.
a Reference not displayed b Reference not displayed, field 664 used c Reference not displayed, field 663 used d Reference not displayed, field used n Not applicable
Control subfield ‡w in the 7xx fields contains two character positions designated as ‡w/0 and ‡w/1.
- 7xx character positions - Table
Position Code Description 0
Link Display Code
- Controls the suppression of a link display.
a Link not displayed b Link not displayed, field 788 used c Link not displayed, non-7xx field used n Not applicable 1
Replacement Complexity Code
- Indicates whether heading replacement requires review.
a Heading replacement does not require review b Heading replacement requires review n Not applicable