Two constraints to design around

The model builder refuses anything ambiguous. It checks these two rules when it builds the model, so you find out at startup:

1. Two parent interfaces may not declare the same property name. If ILocatable and ITagged both declared CountryCode, any type implementing both would fail to build. Keep facets disjoint, or move the shared member into a base interface that both extend.
2. A property cannot be declared again further down. It is defined once, on the type that first declares it. To change some of its attributes for a derived type, use [PropertyOverride] (§3.1).