By convention, the name of a Texinfo file ends with (in order of preference) one of the extensions .texinfo, .texi, .txi, or .tex. The longer extensions are preferred since they describe more clearly to a human reader the nature of the file. The shorter extensions are for operating systems that cannot handle long file names.
In order to be made into a printed manual and an Info file, a Texinfo file must begin with lines like this:
\input texinfo
@setfilename info-file-name
@settitle name-of-manual
The contents of the file follow this beginning, and then you must end a Texinfo file with a line like this:
@bye
@setfilename line provides a name for the Info file and
tells TeX to open auxiliary files. All text before
@setfilename is ignored!
@settitle line specifies a title for the page headers (or
footers) of the printed manual, and the default document description for
the `<head>' in HTML format. Strictly speaking, @settitle
is optional—if you don't mind your document being titled `Untitled'.
@bye line at the end of the file on a line of its own tells
the formatters that the file is ended and to stop formatting.
Typically, you will not use quite such a spare format, but will include mode setting and start-of-header and end-of-header lines at the beginning of a Texinfo file, like this:
\input texinfo @c -*-texinfo-*-
@c %**start of header
@setfilename info-file-name
@settitle name-of-manual
@c %**end of header
In the first line, `-*-texinfo-*-' causes Emacs to switch into Texinfo mode when you edit the file.
The @c lines which surround the @setfilename and
@settitle lines are optional, but you need them in order to
run TeX or Info on just part of the file. (See Start of Header.)
Furthermore, you will usually provide a Texinfo file with a title page, indices, and the like, all of which are explained in this manual. But the minimum, which can be useful for short documents, is just the three lines at the beginning and the one line at the end.