% extra.sty : Isabelle Manual extra macros for non-Springer version
%
\typeout{Document Style extra. Released 17/2/94, version of 22/8/00}

%%Euro-style date: 20 September 1955
\def\today{\number\day\space\ifcase\month\or
January\or February\or March\or April\or May\or June\or
July\or August\or September\or October\or November\or December\fi
\space\number\year}

%%%Put first chapter on odd page, with arabic numbering; like \cleardoublepage
\newcommand\clearfirst{\clearpage\ifodd\c@page\else
    \hbox{}\newpage\if@twocolumn\hbox{}\newpage\fi\fi
    \pagenumbering{arabic}}

%%%Ruled chapter headings 
\def\@rulehead#1{\hrule height1pt \vskip 14pt \Huge \bf 
   #1 \vskip 14pt\hrule height1pt}
\def\@makechapterhead#1{ { \parindent 0pt 
 \ifnum\c@secnumdepth >\m@ne \raggedleft\large\bf\@chapapp{} \thechapter \par 
 \vskip 20pt \fi \raggedright \@rulehead{#1} \par \nobreak \vskip 40pt } }

\def\@makeschapterhead#1{ { \parindent 0pt \raggedright 
 \@rulehead{#1} \par \nobreak \vskip 40pt } }