A «Role» is a kind of «Facet» that is played by exactly one identifiable thing. It is the way some identifiable thing participates in relationships with other concepts, and may specify the necessary conditions for playing the «Role» concept.
When the necessary conditions for playing a «Role» concept are met, the identifiable thing will be a member of that concept. When the necessary conditions for playing a «Role» concept are not met, the identifiable thing will not be a member of that concept.
When it is necessary for an individual to have properties that are existentially dependent on a relationship, a role being played can be treated as a separate qua entity (i.e., a thing in a role). When it is not necessary to have properties that are existentially dependent on a relationship, the identifiable thing playing the role can be a member of the role concept.