If you do not explicitly set it, the ABL session identity is undefined, with the client-principal handle value returned by the SECURITY-POLICY:GET-CLIENT( ) method set to the Unknown value (?). You can also clear an existing ABL session identity, which resets the effective session identity to the unknown identity.
To set an ABL session identity, you must build a session domain registry for the session at run time in order to assert and validate an authenticated user identity as a valid ABL session identity for SSO, and optionally as a database connection identity. For more information, see
Setting up and using domain registries.