We've actually tested this at our library; 952c is the item type, and 947 holds the rest of the item info. It turns out that if anything on the same tag as the item is mapped to any other table, things break horridly. The MARC Check does show this, just not very clearly (some weird grumbling in the itemnumber check). Other than that, we haven't had any problems. None of Koha seems to assume that 952 must be the item tag. -- Jesse