From NSDLWiki

aggregatorFor

The aggregatorFor relationship identifies a resource that represents, or is a manifestation of, an aggregation.

Types (Subject) that may contain this relationship 

Aggregator

Types (Object) that this relationship points to 

Resource

Predicate Namespace 

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

Cardinality 

At most one aggregatorFor relationship may be in a given Aggregator.

Usage and Semantics

If an Aggregator is associated with a resource, that means that the Resource's content provides some concrete representation of that aggregation. For example, suppose somebody is creating a wiki page about clouds, and has chosen some cloud resources from the the repository to discuss on the page. If that wiki page were itself a resource in the repository, then it would be possible to construct an Aggregator containing those resources and associate that group with the wiki page in the repository. Thus, the group or cloud resources would be associated with a wiki page that describes them as a group