[CatSIG] Holdings 852 $2 Code list

Hallo Cataloguers, Does anyone know where I can find a code list for values to go in the $2 subfield of the 852 field in a holdings record, if I were to use the first indicator "7" e.g. 852 7_ $b CMap $h 830 $2 (Boggs & Lewis) or am I completely on the wrong tack as far as the usage of this goes? Trouble is, there is no value in the first indicator list for Boggs and Lewis. We've been (ouch!) using "1", the Dewey code as the nearest thing. Pamela Pamela Treanor Cataloguing Section Information Resources University of Otago Library P.O. Box 56 Dunedin 9054 New Zealand pamela.treanor@otago.ac.nz (03) 479 9781