Koha is letting catalogers enter multiple main entry tags. Only one 1XX tag is permitted according to cataloging rules. It would be nice to have a way to link fields together in the framework and say that 1 is required but that all can't be filled in.
This bug is present today. It´s possible a solution? Thks Paul
Technically, Koha doesn't enforce cataloguing rules. It just focuses on MARC data. I suppose it could be interesting to add some kind of catalogue rule checker that gets called either manually or when trying to save a record.