[Koha] KOHA 1.2.3

Hello, I'm interested in knowing if KOHA has boolean operators or a search system by subject that is known to anyone. I have found that AND is the only operator that can be used to group subjects etc. Can anyone shed some light on this. I am only working voluntarily so haven't had a chance to go very far with this to date. Also, in Dewey classification, the Class and Subclass. How are people getting on with periodicals when there may be letters and numbers in the subclass. We can only use numbers/letters pertaining to each division respectively. We have struck a few problems, potentially bugs, but overall very happy with Koha and are hoping to upgrade to KOHA 2. whenever it is released. Thankyou Heather (Student librarian)