Dear all, This is somewhat of a librarian question, rather than a Koha technical question. Please let me know if there's a newsgroup (OCLC?, LOC?) that would more appropriately field this sort of question. Otherwise, here it is, a re-write of one that I asked on 26-April: As part of our migration to Koha, we're implementing MARC standard. Over many years we've input our own Subject and keyword material to facilitate searching. 1) We suppose it's a good idea to use Z39.50 searches to "upgrade" migrated records to MARC 2) We don't want to overwrite our own proprietary information that was mapped/migrated to MARC 1xx - 8xx. (As I understand it, 9xx is not affected on Z39.50 updates. In addition to 9xx, is a Z39.50 update of a specific record limited by the Koha MARC biblio framework that's being used? ) Do we simply keep data from the old system in 9xx, and then write customized searches to include 9xx along with 650 subject, 5xx General Notes, etc. Or should we simply not bother with doing the Z39.50 searches for migrated holdings. i.e. only do Z39.50 with new entries added one-by-one within Koha. Thanks very much, Nelson Cape Town, South Africa