The U.S. MARC Advisory Committee includes the American Library Association's (ALA) Machine-Readable Bibliographic Information (MARBI) committee, US national libraries, the Library and Archives Canada, British Library and the National Library of Australia, the large bibliographic networks such as OCLC and RLIN, library associations such as the Music Library Association and Special Libraries Association, and library system vendors.
The common characteristic of these groups is that they are large scale users of MARC, thus have serious concerns for the development and stability of the format. The Library of Congress also maintains an electronic discussion forum for the formats (MARC@LOC.GOV) that has over 800 subscribers, opening discussion to all interested librarians.
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 and in paper form. The documents are available for comment on the electronic forum for approximately two months before each of the meetings that are held twice a year by the U.S. MARC Advisory Committee for discussion of proposals. An actual formal vote is taken by the ALA MARBI part of the Committee; however, the Library of Congress and the National Library of Canada has the final authority on changes.