Assignment Users
There are three roles which have to deal with the various content objects:
1. The description author
2. The submitter
3. The reviewer (i.e. that person who reviews the submission, returning it to the submitter with some sort of evaluation or feedback)
In the simplest case the author and reviewer are the same person, and each submitter is an individual. More complex cases can be found in such things as group assignments, peer review, etc., while assignments might be authored by external users (e.g. publishers) or by a coordinating teacher who does not grade or assess individual assignments (e.g. a teaching assistant might do this instead).
In the context of a particular assignment a user will typically (but not necessarily - e.g. peer reviewing another team's submission while they do the same for you) be either a submitter or reviewer, but not both. When taken across all assignments they occasionally serve in both roles. Taken across all collaboration spaces on the system - whether course sites or not - the most typical user may frequently serve in both roles, and this presents its own design challenges for a synoptic or dashboard view.