Hi,
After working to understand the current SNAP Data Model (in particular the current proposed XML Schema), I decided to distill it into a single document with fewer types. I've had some success, so I've post the Schema, and a sample instance document on the Twiki attached to the IVOATheorySimulationDatamodel page:
Schema
http://www.ivoa.net/internal/IVOA/IVOATheorySimulationDatamodel/
Simulation.xsd
Sample Instance
http://www.ivoa.net/internal/IVOA/IVOATheorySimulationDatamodel/
SimulationInstance.xml
At the bottom of the page there are links screen shots of the elements and data types, which help to show they're relations.
This schema keeps the method of characterization as the SNAP model, by defining the axes up front (or, at the top), but is less abstract. It treats a simulation and its data as the results of running a program with defined input parameters, and does not try describe everything about the method and numerical representation. To me, these are things defined by the program (the software), and could be handled by defining separate VOResource for "Program" or "Software Project".
If this works looks interesting to anyone, I would be glad to write up a fuller description, any even put some documentation in the Schema and instance documents.
I plagiarized heavily from both them SNAP Data Model, and the Spectral Schema, so any credit should go to Gerard and the DAL, Data Modeling group, and annoyed comments sent my way.
--Rick