A statement that includes the AS DEFAULT option has no effect on the logon access granted to or revoked from specific user names. A user named in a GRANT LOGON statement can always access the applicable client system even if that client has a default of REVOKE, and a user named in a REVOKE LOGON statement cannot access the applicable client system even if that client has a default of GRANT.
When a GRANT LOGON statement is submitted, the system checks that the requesting user has EXECUTE privilege on the system macro associated with that statement. However, no checks are made on whether the user names defined in the statement apply to users owned by the requesting user. If the submitted statement cannot be verified because, for example, it specifies a non-valid user name or an invalid host ID, no action is taken on the statement.