Interpretation of cardinality on specification

In the calls, the cardinality on specifications was always intended to relate to the existence of elements in the applicability set.

**Prohibited**, would mean that no elements should be matched, regardless from any facets in the requirements list.
**Required**, would mean that at least one element would be matched, and then all requirements should also be matched.
**Optional**, would mean that at if elements would match, all their requirements should also be matched.

The test cases, seem to suggest differently.

The team needs to decide which one is the most expressive approach, and document the choice made.