This specifies a new Phase IV synonym for the node.  This replaces any
 current Phase IV synonym value in the node registration.  Phase IV
 synonyms can be used in place of fully specified node names, particularly
 with applications that do not support full node names.

     SYNONYM synonym-name

 The synonym must be from 1 to 6 letters (A to Z) or digits (0 to 9), with
 at least one letter.  To specify that the node has no Phase IV synonym,
 use two quotation marks ("") for the Phase IV synonym name.  For example:

     SYNONYM MLHUB
     SYNONYM ""

 If the SYNONYM parameter is not specified, the current synonym name for
 the node is not modified.