...
The SHR (with the IOL) plays a dual role of both Document Registry and Document Repository. As a registry the SHR can store metadata about documents, while as a repository, the SHR can provide the storage for these documents. The SHR must switch between roles depending on the transaction, and should, if required, be able to perform just the role of registry (or repository) with for an external 3rd party repository (or registry).
...