fpc/docs/packages/fancyhdr/extramar.sty

% extra marks for latex.
% This gives you two additional marks. \extramarks{m1}{m2} define two extra
% marks for headers/footers (especially for use with fancyheadings), which
% can be retrieved by \firstxmark and \lastxmark resp. Usually m1 is what
% would appear at the top of the page, m2 at the bottom of the page.
% Typical usage:
% \pagestyle{fancy}
% \lhead{\firstxmark}
% \rfoot{\lastxmark}
%
% \extramarks{}{Continued on next page...}
% text text text text text text text text text text text text text text text 
% text text text text text text text text text text text text text text text 
% text text text text text text text text text text text text text text text 
% text text text text text text text text text text text text text text text 
% text text text text text text text text text text text text text text text 
% \extramarks{Continued}{}
% This package also provides two extra handles to the standard LaTeX marks,
% namely \firstleftmark and \lastrightmark (the standard \leftmark and
% \rightmark of LaTeX always give you the last and first, respectively.
% These are the complementary values).

% Note: there is an extra command \topxmark, but this doesn't work properly
% if marginpars or floats are used, as LaTeX clobbers TeX's topmark in this
% case. 

\def\@leftmark#1#2#3#4{#1}
\def\@rightmark#1#2#3#4{#2}

\def\markboth#1#2{{\def\protect{\noexpand\protect\noexpand}
     \let\label\relax \let\index\relax \let\glossary\relax
     \expandafter\@markboth\@themark{#1}{#2}
     \mark{\@themark}}\if@nobreak\ifvmode\nobreak\fi\fi}
\def\markright#1{{\def\protect{\noexpand\protect\noexpand}
     \let\label\relax \let\index\relax \let\glossary\relax
     \expandafter\@markright\@themark{#1}
     \mark{\@themark}}\if@nobreak\ifvmode\nobreak\fi\fi}
\def\@markright#1#2#3#4#5{\gdef\@themark{{#1}{#5}{#3}{#4}}}
\def\@markboth#1#2#3#4#5#6{\gdef\@themark{{#5}{#6}{#3}{#4}}}
\def\leftmark{\expandafter\@leftmark\botmark{}{}{}{}}
\def\rightmark{\expandafter\@rightmark\firstmark{}{}{}{}}
\def\firstleftmark{\expandafter\@leftmark\firstmark{}{}{}{}}
\def\lastrightmark{\expandafter\@rightmark\botmark{}{}{}{}}

\def\@themark{{}{}{}{}}

\def\extramarks#1#2{{\let\protect\@unexpandable@protect
     \let\label\relax \let\index\relax \let\glossary\relax
     \expandafter\@markextra\@themark{#1}{#2}
     \mark{\@themark}}\if@nobreak\ifvmode\nobreak\fi\fi}
\def\@markextra#1#2#3#4#5#6{\gdef\@themark{{#1}{#2}{#5}{#6}}}
\def\firstxmark{\expandafter\@firstxmark\firstmark{}{}{}{}}
\def\topxmark{\expandafter\@firstxmark\topmark{}{}{}{}}
\def\lastxmark{\expandafter\@lastxmark\botmark{}{}{}{}}
\def\@firstxmark#1#2#3#4{#3}
\def\@lastxmark#1#2#3#4{#4}