item-level callnumbers are really the only valid type of callnumber, since callnumber refers to shelf location and bibs don't have shelf location. There's a separate concept of 'classification' that can appear at the bib level, but it's really not used very much in practice in libraries, other than as a reference point. Shelf browse lists, etc., are generated from the item-level itemcallnumber, which should always be populated for every item.
Now take the example of Lists in the OPAC: When you open a list for viewing, you're looking at a list of titles. If call numbers are only relevant at the item level, then does it make sense to simply leave out call number information from the display of Lists? -- Owen -- Web Developer Athens County Public Libraries http://www.myacpl.org