The file machid.shar is a shell archive of the sources to the
machid server, an example presented as part of the multi-threaded
servers tutorial at the Second Usenix Mach workshop in November
1991 at Monterey, CA.  This is a toy service for associating
human-usable names (MachIDs) with ports.  It is similar to
(although simpler than) the machid server that is part of the
Mach 3.0 "USER" distribution.  The archive also contains a toy
client to excercise the server.