Default: X.121 Value: Manual or X.121 Mechanism by which the destination DTE address is to be derived. manual The destination DTE address is supplied manually by means of the destination characteristic. X.121 The destination DTE address is derived by an algorithm from an NSAP address in X.121 format. X.121 address mapping may only be specified with address prefixes of 36, 37, 49, 52 and 53. Example: set x25 access reachable address x121 mapping X . 121