General Vc Interface Dc User Data

This attribute contains the user data which is appended to the call request packet that is presented to the called (destination) DTE. User data can be a 0 to 128 byte string for fast select calls; otherwise, it is 0 to 16 byte string. Fast select calls are indicated as such using the X.25 ITU-T CCITT facility for 'Reverse Charging'. The length of the user data attribute is not verified during service provisioning. If more than 16 bytes of user data is specified on a call without the fast select option, then the call is cleared with a clear cause of 'local procedure error', and a diagnostic code of 39 (as defined in ITU-T (CCITT) X.25).