[Koha] question about database fields

In the wiki at http://wiki.koha-community.org/wiki/Holdings_data_fields_%289xx%29 it says: "The connection between the marc field and the sql tables 'items' is done with the frameworks. You can't change the sql table 'items' but YOU can change the marc field and subfields." However, we have found that the size for itemcallnumber is too small for some of our call numbers. Does this mean that we cannot increase the size of the field? Thanks in advance. -- Linda Culberson lculber@mdah.state.ms.us Archives and Records Services Division Ms. Dept. of Archives& History P. O. Box 571 Jackson, MS 39205-0571 Telephone: 601/576-6873 Facsimile: 601/576-6824