> is more about restricting HOW a deployable should be mapped whereas mustBeMapped

I see your point about mR - the thing about `mustBeMapped` to me is that it sounds like a boolean. `mappingStrategy`? `mappingModel`?

Or, changing themes again, `requiredInstancesPerEnvironment`? `requiredMappingsPerEnv`? With values `NONE, AT_MOST_ONE`, ..?

In fact, in that case you could make the model a little easier and simply expose _two_ properties: `minNumInstances` and (optionally) `maxNumInstances` (integers >= 0) and use those?