PROV-ISSUE-384 (prov-role-in-attribution): prov:role in attribution or not? [prov-dm]

PROV-ISSUE-384 (prov-role-in-attribution): prov:role in attribution or not? [prov-dm]

http://www.w3.org/2011/prov/track/issues/384

Raised by: Luc Moreau
On product: prov-dm


In the example, 
http://www.w3.org/TR/prov-dm/#anexample-attribution,
we write:
wasAttributedTo(tr:WD-prov-dm-20111215, ex:Paolo, [prov:role="editor"])


But in
http://www.w3.org/TR/prov-dm/#term-attribute-role
we say:
The attribute prov:role denotes the function of an entity with respect to an activity, in the context of a usage, generation, association, start, and end.


So, 
1. Do we want to accept prov:role in Attribution?
  (or, it's not a prov:role but prov:type we should use?)

2. If yes, does it mean the definition of prov:role needs to be changed?  where is the activity?

3. Should we have an optional activity in Attribution?

Luc