The systemid file may contain a site name (site_name) and up to four different machine names (machine_name1-machine_name4).
The file must contain at least one machine name. The other machine names are optional, serving as alternate names for the same machine. The file must contain a site name if more than one machine name is given or if the network is connected to another through a UUCP link. The site name, when given, must be on the first line.
Each name can have up to eight letters and numbers but must always begin with a letter. There is never more than one name to a line. A line beginning with a number sign (#) is considered a comment line and is ignored.
The Micnet network requires one systemid file on each system in a network with each file containing a unique set of machine names. If the network is connected to another network through a UUCP link, each file in the network must contain the same site name.
The systemid file is used primarily during resolution of aliases.
When aliases contain site and/or machine names,
the name is compared with the names in the
file and removed if there is a match.
If there is no match, the alias (and
associated message, file, or command) is
passed on to the specified site or machine for
further processing.