[Koha] Import matching rule for 001 tag

I'm having trouble getting this to work with the following settings: Search index: Control-number Score: 101 Tag: 001 Subfields: [blank] Offset: 0 Length: 0 [blank does not work either] Normalization rule: Control-number I found an old post from Galen suggesting that that the Length parameter be changed, but since OCLC numbers come in varying lengths (7,8,9 digits?), I'm not sure how this would work. Any thoughts? (And yes, I'm aware that the 001 tag is not fool-proof. In this case, however, it suits our purposes well.) Many thanks! Cab Vinton, Director Sanbornton Public Library Sanbornton, NH Life is short. Read fast!