Control sequences come in two flavors. The first kind, like |\input|,
is called a {\sl^{control word}\/}; it
consists of an escape character followed by one or more {\sl letters}, followed
by a space or by something besides a letter. \ (\TeX\ has to know where the
control sequence ends, so you must put a space after a control word if
the next character is a letter. For example, if you type `|\inputMS|',
\TeX\ will naturally interpret this as a control word with seven
letters.) \ In case you're wondering what a ``^{letter}'' is, the answer