I wrote my own system that started out as a book catalogue but morphed to encompass archive items and physical objects. I allow hierarchy by allowing some thing to be enclosed in another even though it is in one table and use the code to find this if needed. It also has the concept of subjects, of a book, of a picture etc it is easy to tie stuff together by abusing the dewey field eg 621.833 will get all books, manufacturers catalogues, national standards etc on gear cutting Best not get to religious on categories from any one area Dave Caroline