A call number can go in fields 050, 082, 090, 092 and many others in the bibliographical record. That is the Library of Congress Classification number, Dewey number, National Library of Medicine number, etc. Not necessarily the number you or any library, is using. The call number for your item goes into the item record. 852 in many systems, maybe 949 in Koha. As for your numbering system.... Having different numbers won't matter if folks can't browse the shelves. Do you let users browse? If not than having different copies of a video with 48 and 218 as call numbers would be OK. If people browse, then how do you want them arranged on the shelf? By title? Then a classification system that arranges by that would be best. Maybe by topic? That is more complex. Deciding on just what the topic is can be tricky. Creating a classification scheme for a topic is a complex task. Finding one that works a chore. A good tool to generate numbers if shelving by title would be the free Windows OCLC Dewey Cutter Program. http://www.oclc.org/dewey/support/program/ You should give all copies of a title the same call number and use the barcode to distinguish among them. The barcodes should be different for each item. David Bigwood dbigwood@gmail.com Catalogablog http://catalogablog.blogspot.com