This is fancyhdr, a replacement for fancyheadings. 

I still still intend to make sometime in the future a real .dtx of it,
including the minimal documentation. The current documentation is in
fancyhdr.tex, but this contains much more material than the fancyhdr doc.
When the fancyhdr.dtx is ready, I will rename fancyhdr.tex into something
like pagelayout.tex to get it more in line with the title (Page Layout in
LaTeX).

fancyhdr is 99% compatible with fancyheadings. The only incompatibility is
that \headrulewidth and \footrulewidth and their \plain... versions are no
longer length parameters, but normal macros (to be changed with
\renewcommand rather than \setlength).

Although all the other old fancyheadings commands continue to work you are
advised to use the new syntax as described in fancyhdr.tex, because this is
much easier to use in complicated cases. The old way of doing is no longer
described in the manual, except for the simplest use of \lhead etc.

In order to latex the documentation you need to install a copy of
tex-archive/macros/latex/contrib/other/misc/boxedminipage.sty

The fixmarks.sty is now obsolete, as it is superseded by David Carlisle's
fix2col.sty (tex-archive/macros/latex/contrib/supported/carlisle/) so it is
no longer included here.

fancyhdr.sty version 3 and extramarks.sty version 2 are the packages
as described in the second edition of The LaTeX Companion.

LICENCE: All files in this package may be distributed under the terms of
the LaTeX Project Public License, as described in lppl.txt in the base
LaTeX distribution. Either version 1 or, at your option, any later
version.
-- 
Piet van Oostrum.
<piet@cs.ruu.nl>
http://www.cs.ruu.nl/~piet