In my experience, Koha needs the subfield "o" - Full call number. I migrate from CDS/ISIS DOS and the LC callnumber (050ab) was import in both fields, one for MARC21 and one for KOHA. When I add a record the LC callnumber was copied automaticaly to subfield "o" subfield in the Add ITEM secction. Try a search in my OPAC and export to MARC to study the format. Salduos, FAOA Biblioteca Loyola System librarian KOHA OPAC http://clavius.tij.uia.mx