What are additional features of Deliverable Type Class - Document ?

I want to know - what features are available for deliverables with type (with deliverable type class- Document) ?

For example, for Item class we can initiate purchase requisition and so on.

Documentation (implementation guide and project management guide) are not  informative for this question.

I tried to create deliverables (document class), additional attachments page region appear. But this new region is identical to standart Attachments region (available for all deliverable types).