[firebird-support] How to retrieve list of users granted with the admin role

[r...@xs4all.nl [firebird-support]]

As SYSDBA I like to know which users are granted in the past with the ADMIN 
ROLE (as in CREATE USER Test1 PASSWORD 'test' GRANT ADMIN ROLE).
 

 I guess those users have the system defined RDB$ADMIN role assigned in the 
security database, but I do not have direct access to the security databae to 
check this. Also the system table SEC$USERS does not give me a clue.
 

 Any other suggestions how to retrieve those users with admin role?
 

 Thanks!
 Robert