So I’m trying to figure out what a “GPO Item Number” is, and what it’s relationship to a “Sudoc number” etc is.
Contrary to the implications of ‘item number’, it looks like more than one document can share the same GPO Item Number. I think more than one document can also share the same SuDoc class mark? What do these things actually mean, what’s going on?
GPO Item Number is stored in MARC field 074, a field in fact reserved just for that. The MARC documentation tells me “The GPO item number is not the same as the unique number that identifies each entry in the Monthly Catalog of Government Publications, nor is it an order number.”
Okay, great, now I know what it’s NOT, but what the heck IS it? And why was this value chosen to be recorded in MARC instead of, say, “the unique number that identifies each entry in the Monthy Catalog”, which would seem to be a lot more useful to me, but which isn’t in fact recorded in our MARC (doesn’t even have a place to record).
Can anyone help me out there? Any gov docs librarians out there? Google isn’t doing much for me.