Muhammed,
You've spotted that roles can contain other roles - a very powerful facility (one could say "vital facility")
The linkage is maintained via an "mtm" type table called sys_user_role_contains
Out-of-box the ROLE view has ONE Related List called "Contains Roles" which points "down" the hierarchy.
I find it VERY useful to add the "reverse" related list - "Contained By" since that allows me to look "up" the hierarchy.
This may well give you all the answer you need, if not try writing a report around the mtm table.
Mike
