is_in_collection
Use it like this:
- [ #is/_in_collection :: Thing ] or
- [ is_in_collection :: Thing ]
A sub property of object. The collection target of the action.
Relation describes that: [ #has_/domain :: UpdateAction ] ( #has_/name :: is_in_collection ) ( #has_/range :: Thing )
[ #is_/sub_property_of :: object ]