One component of our budding academic site is a searchable database of publications authored by department members. Publications come in various flavours: journal articles, conference proceedings, books, book chapters, etc. All of these share certain properties while others are unique. Question: In terms of ZClasses, is it best to create an abstract Publication ZClass with common data and methods and then subclass the various flavours? In addition to publication details, I also want the option of encapsulating the data files, be it in PDF, MSWord, ASCII, TeX format, etc. Question: Rather than create a slew of File-like products in the root Product folder, should I again create an abstract class and subclass for each Mime type a la the PDF example used in: http://www.zope.org/Members/lstaffor/zProperties The same applies for People, variants of which include staff, students, alumni, visitors, etc., with the difference that people can migrate from one class to another (student to alumni). Summary Question: Generally speaking, rather than create a slew of ZClasses in the root Product folder, should one liberally subclass? Advice on these critical design decisions is most appreciated. Darran.