SET(UNDEFINED_KEY)

  Determines the action taken when an undefined key-map key is used.

  Syntax

     SET (UNDEFINED_KEY, string [, action])

  Parameters

     string     The key-map list for the procedure.

     action     A string, buffer, range, or program specifying the action to
                be taken on an undefined key.  If you specify a string,
                buffer, or range, it is compiled.  The default is to display
                a message "Key has no definition."

  Example

  The following statements cause the default message for an undefined key to
  be displayed when an undefined key is used:

     IF GET_INFO ("tpu$key_map_list", "undefine_key") <> 0
        THEN
           SET (UNDEFINED_KEY, "tpu$key_map_list");
     ENDIF;