From NSDLWiki

memberOf

The memberOf relationship signifies that an object is a member of an aggregation.

Predicate Namespace 

http://ns.nsdl.org/api/relationships#

Cardinality 

Zero or more

Found in 

Agent, Aggregator, Metadata, MetadataProvider, Resource

Values 

Handle of an Aggregator

Usage and Semantics

The memberOf relation exists in the object that is a member, and points to the Aggregator containing it. As such, adding this relationship to an object can be seen as changing the membership of the Aggregator it points to, rather than changing the object itself. Changing the membership of an Aggregator, then, does not involve an operation on the Aggregator object itself, but to its member. Consequently, any authorization rules related to adding or removing a memberOf to some object are determined by the permissions of the Aggregator the relationship points to, rather than the object itself.