Controlled-list Data Elements
Certain data elements contain data from controlled lists maintained by designated agencies, e.g., the MARC Code List for Geographic Areas in field 043 (Geographic Area Code). These elements are indicated at the field or subfield level in MARC 21 and only values from the designated lists may be used. If a change or addition is desirable for a list, the maintenance agency for the list should be consulted.
Record Level Requirements
User groups may have full level and minimal level record requirements to promote consistency across cataloging agencies. These should be widely publicized for all possible interchange partners to be aware.