SharePoint security can be tricky business.
Here are a few URLs that helped me going:
- InfoWorker Solutions: SharePoint ACLs: RoleDefinitions, RoleAssignments, Inheritance.
- http://msdn.microsoft.com/en-us/library/ms457294.aspx
- http://msdn.microsoft.com/en-us/library/ms414036.aspx
–jeroen
The Wiert Corner - irregular stream of stuff 