Re: generic modelling of data models; enforcing constraints dynamically...

I guess it IS quite overengineered indeed...

What I'm trying to do is to facilitate different fieldwork methodologies for archaeological research (on project basis); there is no final agreement on data structure and semantics; however, on a meta-level all choices are rational and can be modelled... Infact, all models can be related to each other: that's where the "hybrid" part comes in: I wish to implement the common denominator (90%) and then further extend this, enabing specific data model implementations -- including checks for data integrity.