The MARC Advisory Committee (MAC) advises the MARC Steering Group concerning changes to the MARC 21 formats. The MARC 21 formats for Bibliographic, Authority, Holdings, Classification, and Community Information data are maintained for the MARC 21 user communty based on broad, open discussion of issues. The MARC Steering Group is composed of the Library of Congress, Library and Archives Canada, British Library, and the Deutsche Nationalbibliothek.
The Terms of Reference for the MARC Advisory Committee, detailing its membership and procedures, were drafted by the MARC Steering Group in 2013.
The MARC Advisory Committee membership includes representatives from national libraries, various library associations, and library system vendors and networks.
The common characteristic of these groups is that they are large scale users of MARC, and thus have serious concerns for the development and stability of the format. The development of the MARC 21 formats is an international effort with avenues for all MARC 21 users to substantially contribute to it. The Library of Congress maintains the MARC Forum, an electronic discussion list for the formats (MARC@LOC.GOV) that has over 1300 subscribers, providing a conduit for broad, open discussion of proposed changes and other issues for all interested users around the world.
Proposals for changes to the format may originate from any user. Library of Congress staff write, review, and/or edit proposals and distribute them electronically. The documents are available for comment on the electronic forum for approximately one month before each of the meetings that are held twice a year by the MARC Advisory Committee for discussion of proposals. Although the MARC Advisory Committee votes on changes, the Library of Congress, Library and Archives Canada, British Library, and the Deutsche Nationalbibliothek have the final authority on any changes which are made to the format.
Proposals and discussion papers for the MAC semiannual meetings should be submitted directly to the Network Development and MARC Standards Office at the Library of Congress, or to the other MARC Steering Group members.
From 1973-2013, the MARC Advisory Committee included the MARBI (Machine-Readable Bibliographic Information) Committee, an interdivisional committee of the American Library Association (ALA). Semiannual MARBI meetings were held at ALA conferences, where proposed changes to the MARC formats were reviewed, evaluated, and voted on by MARBI members, with non-MARBI members of the MARC Advisory Committee serving an informational role. When MARBI ceased to exist in 2013, the MARC Advisory Committee took on the responsibility of continuing MARBI's mission to foster open discussion about the MARC standard and to review and vote on proposed changes to the MARC formats at the semiannual ALA conferences.