INFO(5) File Formats Manual INFO(5)

info - readable online documentation

The Info file format is an easily-parsable representation for online documents. It can be read by emacs(1) and info(1) among other programs.

Info files are usually created from texinfo(5) sources by makeinfo(1) , but can be created from scratch if so desired.

For a full description of the Texinfo language and associated tools, please see the Texinfo manual (written in Texinfo itself). Most likely, running this command from your shell:

info texinfo
or this key sequence from inside Emacs: 
M-x info RET m texinfo RET
will get you there.

http://www.gnu.org/software/texinfo/

Please send bug reports to bug-texinfo@gnu.org, general questions and discussion to help-texinfo@gnu.org.

info(1), install-info(1), makeinfo(1), texi2dvi(1),
texindex(1).
emacs(1), tex(1).
texinfo(5).

GNU Info FSF