Oh, I am a terrible pedagogue.

The idea is, basically, to build something that follows a specification/rule system. It builds models using parts mapped onto objects.

It has support for changing an object tree using the rule system.

The output is in XML. A simple cgi user interface, first.

This specification for data can be defined as: Superset of XML Schema, with code that do tests.

After designing and writing an app that will solve my problem, I find that the data model is easily mapped onto the XML hierarchical tag structure. (-: A long and hard way to rediscover XML. :-) A version 2 of my program would probably use XML Schemas as part, for the familiarity to users.