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 It looks like we have 9000 records, with another 1000 books from PAVED arts. We generally add about 100 new titles/year. We do have serials, but at this point they are not catalogued. 
What I can tell you by way of an overview is that we have regular books that we catalogue using  DDC. Most of what we have are exhibition catalogues and that is where the problem is. There is at least four different ways of cataloguing them that I have noticed—this is just from the labels (not the database):

1. CAT (to indicate it is a catalogue—and I think this is important info for us); name of the gallery/museum who published it (usually an an acronym); first few letters of the title or artist’s name for solo show

1. CAT; DDC; sometimes also with author/artist, but not museum

1. CAT; museum; last name of artist; first name of artist! (this I’m sure can’t be appropriate)

1. CAT; artist last name; museum; part of title

1. CAT; DDC; author/essayist (not title); museum

No doubt there are a few other variations!
Maybe it don’t even need to send photos, but I have some if you think it’s useful.
So, we do want to maintain CAT and the name of the museum. Moving forward, should we include DDC or simply the title and/or artist? Keep in mind that this is a non-lending, research centre for staff and/or researchers, with no library staff to monitor or to assist. Whatever we use has to be the most useful for an educated (but not library trained) researchers to get the most results from a search. Does DDC help?
Thanks hugely for thinking about this!