As was mentioned in the chapter on command parsing, there are five commands
whose interpretation is fixed by the server: PREFIX,
OUTPUTPREFIX, SUFFIX, OUTPUTSUFFIX, and .program.
The first four of these are intended for use by programs that connect to the
MOO, so-called `client' programs. The .program command is used by
programmers to associate a MOO program with a particular verb. The server can,
in addition, recognize a sixth special command on any or all connections, the
flush command.
The server also performs special processing on command lines that begin with certain punctuation characters.
This section discusses these built-in pieces of the command-interpretation process.