Configuring Compartment Security
You can only add a compartment for a new role. To add a compartment, use the Admin Interface and select Security> Roles> Create and enter a name for the compartment in the compartment field when you define each role in the compartment.
You cannot modify an existing role to use a compartment. To add a compartment to a role, you must delete the role and re-create it with a compartment. If you do re-create a role, any permissions you have on documents reference the old role (because they use the role ID, not the role name). So, if you want those document permissions to use the new role, you need to update those documents with new permissions that reference the new role.