If you are referring to roles like in contexts like Projects, Libraries and Product areas, yes. Its a bit more complicated but each Role you see is actually a group so just WTGroup, or a group of a group. This was my Query Builder report to figure out the relationships. Starting with the Team (wt.inf.team.ContainerTeam), this is the main list of "Roles" for a context. That is linked to a groups (G1) via a RolePrincipalMap object. Finally the group which shares the same name as the role (CCB in my image which is a WTGroup), holds the list of users.
Its a bit complicated so you'll need a few APIs to get your answer.
