|Range of values||
The operating system completely manages the role grants for all database usernames. When a user attempts to create a session, the username's security domain is initialized using the roles identified by the operating system. A user can subsequently enable as many roles identified by the operating system as specified by the parameter
Revocation by Oracle of roles granted by the operating system is ignored, as are any roles previously granted by Oracle.
Oracle identifies and manages the roles.
Oracle Database Administrator's Guide and Oracle Database Advanced Security Administrator's Guide for more information on roles and on setting this parameter