Home Source Codes for Vocabularies, Rules, and Schemes

General Information

Source Code Lists
Arrangement of each Source Code List
Source Code Use
Structure of the Source Codes
Source Code Maintenance


Source Codes contains value lists of controlled vocabularies of terms (e.g., subject terms), codes (e.g., language codes), identifiers (e.g., standard identifiers), or for specific data formulation rules (e.g., RDA) or schemes (e.g., DDC).  The vocabularies, rules, and schemes are generally referred to as the source of the value data, and the source is identified in data formats in order to support interpretation of data values that come from these sources.  The Source Codes are presented as separate lists for different types of sources, for example, subject sources, classification sources, date scheme sources.

Source Code Lists

Abbreviated Title Source Codes
Access Restriction Term Source Codes
Availability Status Code Source Codes
Caption Abbreviation Source Code
Cartographic Data Source Codes
Citation Scheme Source Codes
Classification Scheme Source Codes
Content Advice Classification Source Codes
Copyright and Legal Deposit Number Source Codes
Country Code and Term Source Codes
Curriculum Objective Code and Term Source Codes
Date and Time Scheme Source Codes
Description Convention Source Codes
Entity Type Source Codes
Fingerprint Scheme Source Codes
Format Source Codes
Frequency of Issue Code and Term Source Codes
Function Term Source Code
Gender Code and Term Source Codes
Genre/Form Code and Term Source Codes
Geographic Area Code and Term Source Codes
Holdings Scheme Source Codes
Human Services Code Source Codes
Language Code and Term Source Codes
Musical Composition Form Code Source Codes
Musical Incipit Scheme Source Codes
Musical Instrumentation and Voice Code and Term Source Codes
Name and Title Authority Source Codes 
National Bibliography Number Source Codes
Occupation Term Source Codes
Organization Code Source Codes
Price Type Code Source Codes
Program Code Source Codes
Relator and Role Code and Term Source Codes
Resource Action Term Source Codes
Script Code and Term Source Codes
Standard Identifier Source Codes
Subject Category Code Source Codes
Subject Heading and Term Source Codes
Target Audience Code and Term Source Codes 
Taxonomic Classification Source Codes
Thematic Index Code Source Codes
Transcription Scheme Code Source Codes

Alternative pathways to the Source Code lists are via:

Arrangement of each Source Code List

Entries in the each Source Code list are arranged in alphabetical order by the code and consist of the source code followed by the bibliographic citation for the source documentation.   If online documentation of a source list is known, the citation is linked.

Source Code Use

These codes may be used wherever there is a need to refer to a controlled vocabulary, rule set, or scheme, but in particular they are intended for use with MARC and MODS/MADS data.

For newly assigned codes, a date is given before which the code should not be included in exchange records. The date represents a 60-day waiting period required to allow MARC and MODS/MADS implementers time to add newly assigned codes to any validation tables they may use to check the codes recorded in records. Implementers may use newly assigned codes in their internal systems immediately as long as records containing new codes are not distributed until after the waiting period.

Structure of the Source Codes

The general guidelines for codes contained in this documentation are the following.  Codes are composed of lowercase alphabetic characters, and, in some cases, numeric characters 0 through 9 and the hyphen (-).  Codes vary in length, but most codes have a maximum of 12 characters.  Codes are usually based on the title or numbering of the documentation.

The code may be followed by the addition of edition, language, or date of publication of the source documentation. The code is separated from the addition by a slash (/).  Examples:


Instead of the full name of a language, the 3-character MARC language code should be used when the code addition for language is needed. Example:


Omission of the edition, language, or year will imply that the assigning institution used the edition that was current when the record was created.

Source Code Maintenance

The Library of Congress is the maintenance agency for the source code lists at the site. All assignments are made as the result of an official request.  Please send requests for the assignment of new source codes and questions about existing code assignments to: Network Development and MARC Standards Office, Library of Congress, 101 Independence Avenue, S.E., Washington, DC 20540-4402, USA; Fax: +1-202-707-0115; Email: [email protected]. Requests for the assignment of a new source code should include a full bibliographic citation for the source documentation or web site for the code or term list, code or term database, scheme (e.g., for classification schedules), or rules (e.g., for description conventions).  For printed sources, include a copy of the title page. For online sources, include the URL.

Notices announcing additions or changes to assigned codes and their related citations are distributed prior to the date they should be used in records in the News and Announcements section of the MARC site.

Home Source Codes for Vocabularies, Rules, and Schemes