texi or texinfo is a format designed (it would seem) specifically
for documenting the emacs editor, and which has been used for
documenting many other freely available software packages.

Because it is un-extensible, and has a fairly small command set, it is
ameanable to convertion to a wide variety of format including info
for emacs and the info command to read, dvi for convertsion to
postscript and printing, and html for WEB viewing.

Texinfo documents are converted to html using the texi2html program,
followed by some csg-doc standard headers and footers being attached
to each page.