From NSDLWiki

Trusted Applications Aggregator

The Trusted Applications Aggregator is an Aggregator that contains any Agents that are deemed to be trusted applications with elevated privileges. As it is just common Aggregator with a specific identity, any Agent can be given permission to add other agents to this list, if so desired.

Deployment Concerns

The exact identity of the Trusted Applications Aggregator is specific to the particular deployment of the repository. For the NSDL, its identity is 2200/NSDL_TRUSTED_APPLICATIONS.