Reference Manual
   CHAPTER 16. System Views     

SYSGROUPS system view

CREATE VIEW SYS.SYSGROUPS ( group_name, member_name )
AS
SELECT g.user_name, u.user_name
FROM   SYS.SYSGROUP, 
      SYS.SYSUSERPERM g, 
      SYS.SYSUSERPERM u
WHERE group_id = g.user_id 
AND group_member = u.user_id

Presents group information from SYSGROUP in a more readable format.