This font is used for file and directory names. This font is
used for commands. This font is used for input the user is
expected to enter. This font is used for “replaceable” text or
variables. Replaceable text is text that describes something
you're supposed to type, like a filename, in which the word
“filename” is a placeholder for the actual filename. The
following fonts are used to denote various programming class
names (CCA names (CCA “ports”), and method names. Also
environment variables are marked up with special fonts. Sometime
we must break lines in computer output or program listings to
fit the line widths available. In these cases, the break will be
marked by a “ character. In real computer output, you see a long
continuous line rather than a broken one. For program listings,
unless otherwise indicated, you can join up the broken lines. In
shell commands, you can use the “ \” and break the input over
multiple lines.