Node names are used to maintain node addressing information in the
 directory service, allowing addressing information to be kept in a
 global repository.

 For those directory services that support hierarchical naming, names are
 generally collected into groups using directories.   Three types of
 directories are used for maintaining node information in a directory
 service.  These are:

   Node name directories, containing node names that hold node information
   Reverse address mapping directories, used to map addresses to names
   Synonym mapping directory, used to map Phase IV synonyms to names

 The names and directories are described in the sub-topics.