SPEM — Section 8.3, page 33

"An Activity is owned by a ProcessRole that is the performer (or owner)"
Mixing "performer" and "ownership" is very confusing. In the metamodel
these two concepts should be clearly distinguished.
The "performer" association should not "derive" from the feature/owner
association. It's more natural to say that activities are owned by the
process (a Package).
Features (such as attributes) in roles could be used for another purpose:
adding specific information on roles
NOTE that this suggested modification need not to impact the UML profile.

see above