OCLC Bibliographic Formats and Standards sets out tags 79X (790-799) and 89X (896-899) as valid for local uses. These ranges should be available for network zone members to use as well. Adopting these ranges will allow catalogers to directly adapt records from WorldCat into a network and add local extensions without having to remap from the OCLC-supported field to a field in Alma, such as a 9XX.

Catalogers primarily use these fields to enter details such as authors with local affiliations (e.g., current faculty members), dissertation advisors or members of dissertation committees, and the college within the institution supervising the dissertation. These are locally-relevant data that are not always relevant in the universal, shared record. Allowing their inclusion enables a network member to highlight what makes the record and information valuable to the institution.

Moreover, the use of a local extension for this data helps protect the data from removal by other network members, and the data are protected if the network record is overlaid by a WorldCat record that doesn't retain that data.