> Jeff,=20 > thanks for these very valuable hints. Both issues that you mentioned > are obviously correct and right on. They are dependent on the > implementation of the "constraint solver". Now, at this point, I am > only thinking of the actual core of such a system. Whereas what you > have mentioned is already two resp. three steps up.=20 >=20 > I'll keep your email anyway since you have exactly described what this > parametric thing is all about. >=20 > Thanks, > Roland Roland, I'm glad my rambling is helping; if only with the big picture. Unfortunately, being an Architect without much programming experience, that's all I can see right now: the big picture. I'm learning a little OO programming via Squeak. But it will be a *long* time before I'll be able to contribute anything in a 'real' programming language that I'm certain y'all will be using. When things get a little farther along, I can certainly help out with testing/documentation/ website stuff- but for now, I can only lurk and blabber about the Forest while everyone else talks about the trees... Jeffrey =20