[Koha] mapping to KOHA

Hi, I am new to KOHA and have a question about mapping from MARC to KOHA. Is it required that item data be mapped to field 952 or can I change this to a different field in the mapping table? I tried doing that and am getting errors, including this one for the itemnum field: * The field itemnum MUST be mapped * The correspounding subfield MUST be in with -1 (ignore) tab Thank you. -- Beth Willis Catalog & Digital Librarian North of Boston Library Exchange, Inc. Danvers, Massachusetts willis@noblenet.org