Introduction:

To understand where revisions and tags fits into our model in a nutshell:

Record contains representations ------------->representation has versions-------------> versions contains files and has revisions -------------> revision is marked by tags.

Revisions and tags:

Versions may have revisions. One or more revisions of a version can exist and they are used to govern necessary workflows and filter their queries. Each revision is uniquely identified by three parts: revision_name , revision_provider and revision_timestamp.

Tags are a set of three boolean flags(accepted, published and mark_deleted) which will be used to mark/tag a revision with a specific state. This tags could be used as filtering criteria.