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 should have been installed on your system along with either the TeX or Texinfo software. TeX uses the backslash, \, to mark the beginning of a command, exactly 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.