Oracle Server Manager Release 2.3.2 Addendum
Controlling Database Security
Users and Roles Folder
When you grant the DBA and RESOURCE roles to a user or role with Oracle7 release 7.2.2 or later, the user or role is also granted the UNLIMITED TABLESPACE system privilege.
When you revoke either role from a user or role, the UNLIMITED TABLESPACE system privilege is also revoked. The UNLIMITED TABLESPACE can also be revoked independent of the DBA and RESOURCE roles.