This document contains a complete list of MARC 21 data elements with codes showing requirements for both national level and minimal level records in the United States. National level records are required to contain sufficient cataloging information to allow them to be used by various agencies: National and world-wide. National level record requirements were developed for most types of material between 1979 and 1981. Requirements for computer files and mixed materials were not added until the 1988 edition of the format. Minimal level records are required to contain only essential cataloging information, although additional data may be provided. The national level and minimal level record requirements presented here are not intended to prevent a cataloging agency from using any valid MARC 21 bibliographic data element. They are provided to facilitate the standardization of the content of MARC 21 bibliographic records.
The list pertains to the February 1999 edition of the MARC 21 Format for Bibliographic Data and includes Update No. 1 (October 2000), Update No. 2 (October 2001), Update No. 3 (October 2002), Update No. 4 (October 2003), Update No. 5 (October 2004), Update No. 6 (October 2005), Update No. 7 (October 2006) and Update No. 8 (October 2007), Update No. 9 (October 2008), Update No. 10 (October 2009)/Update No. 11 (February 2010) and Update No. 12 (October 2010).
MARC 21 record requirements are represented by codes given in separate columns; one for national level records and one for minimal level records. Three different codes have been used to differentiate between data elements that must always be present, that should be present when information is available, and optional data elements. The requirement codes used in this document are defined as follows:
A - Mandatory if applicable
A data element that must be present in a bibliographic record if it is appropriate for the item being described and if the bibliographic information is available. The fill character (|) is not permitted in data elements that are mandatory if applicable.
M - Mandatory
A data element that must be present in every bibliographic record. The fill character (|) is not permitted in mandatory data elements.
O - Optional
An optional data element is not required in a bibliographic record, but may be present if desired. The fill character (|) is permitted in the optional character positions of field 007 (Physical Description Fixed Field), field 008 (Fixed-Length Data Elements, and subfield $7 (Control subfield) of the Linking Entry Fields (760-787).
For the minimal level record requirements, the only sub-elements marked with the M (Mandatory) or A (Mandatory if applicable) are those contained in the fields marked M or A. The other valid MARC 21 data elements are followed by the mark ".", which signifies that the data element does not form part of the minimal level record requirements group. Data elements marked with " ." in the minimal level column are effectively optional and may be used in minimal level records. They have not been marked as optional to make it easier to identify the subset of minimal level data elements.
In MARC 21, a valid value is mandatory in both indicator positions for fields that include indicator positions. In the MARC 21 Format for Bibliographic Data this includes fields 010 through 8XX and any locally-defined fields within the 010 to 999 range that may be used by a cataloging agency. When an indicator position is present but undefined a blank is always used. The fill character (|) is never used in indicator positions in MARC 21. Since valid indicator values are mandatory in all MARC 21 fields (except 001-008), no national-level requirements are given in this document. If a field is present in a record, valid indicator values must be supplied. The individual field descriptions provide listings of valid indicator values.