DB is a utility with which to create and manipulate an alias
    database. Alias databases can either be a personal alias database
    (pointed at by the logical PMDF_PERSONAL_ALIAS_DATABASE) or a
    system alias database. As the format of PMDF alias database is
    used for other PMDF databases (e.g., PMDF_DOMAIN_DATABASE), DB
    can also be used to manipulate non-alias databases.

    DB is invoked by the command

    $ PMDF DB

    and can be exited by either typing Control-Z or issuing the quit-
    program command.