A node's situation as a role player in any given assertion indicates that the subject represented by that node participates in the relationship that is the subject of the assertion, as represented by the assertion's a-node. In an asserted relationship, each role player plays a distinct role; the nature of each role is the subject (called a "role type") of one of the assertion's r-nodes. The relationship itself is an instance of the kind of relationship that is the subject of the assertion's t-node, if any. If the assertion has no t-node, the subject of which the relationship is an instance is not specified.

I may be terribly mistake but I don't read anything here that is
not stated elsewhere. Should not be restating things since that can
cause confusion.