The First Line of a Texinfo File
--------------------------------
Every Texinfo file that is to be the top-level input to TeX must begin
with a line that looks like this:
\input texinfo @c -*-texinfo-*-
This line serves two functions:
1. When the file is processed by TeX, the `\input texinfo' command
tells TeX to load the macros needed for processing a Texinfo file.
These are in a file called `texinfo.tex', which is usually located
in the `/usr/lib/tex/macros' directory. TeX uses the backslash,
`\', to mark the beginning of a command, just as Texinfo uses `@'.
The `texinfo.tex' file causes the switch from `\' to `@'; before
the switch occurs, TeX requires `\', which is why it appears at
the beginning of the file.
2. When the file is edited in GNU Emacs, the `-*-texinfo-*-' mode
specification tells Emacs to use Texinfo mode.