This specifies the base directory or name entry to use when creating
 synonym mapping links for a node name.

     SYNONYM_DIRECTORY syn-dir-name

 The links under this directory are used to map Phase IV synonyms to
 their respective node names.  These directories are used only for the
 DECdns directory service.

 If not specified, the synonym directory name defined in the export file
 is used.  If the export file does not contain a synonym directory name
 definition for the target directory service, then the synonym directory
 name set using the SET DEFAULT command is used.

 For more information, please refer to the NAMES_AND_DIRECTORIES topic.
 See the EXPORT_FILE topic for a description of the synonym directory
 control line.