This specifies the default base directory or name entry to use for the
 synonym mapping link to the 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.

 For example:

     SET DEFAULT DIRECTORY_SERVICE DECDNS SYNONYM_DIR .DNA_NodeSynonym

 For more information, please refer to the NAMES_AND_DIRECTORIES topic.