% LEXIKON.STY
\RequirePackage{ifthen}

\newboolean{first}
\newcommand{\lastchar}{}
\newcommand{\ps@lexikon}
{\renewcommand{\@oddhead}
   {\hfil\textbf{\Large\botmark}%
   \hspace{1cm}\arabic{page}}
 \renewcommand{\@evenhead}
   {\arabic{page}\hspace{1cm}%
   \textbf{\Large\botmark}\hfil} 
 \renewcommand{\@evenfoot}{}
 \renewcommand{\@oddfoot}{}
}

\newenvironment{lexikon}
 {\setboolean{first}{true} 
  \renewcommand{\lastchar}{}
  \newpage\twocolumn
  \let\@oddh\@oddhead  \let\@evnh\@evenhead
  \let\@oddf\@oddfoot  \let\@evnf\@evenfoot
  \pagestyle{lexikon}
 }
 {\end{description}
  \onecolumn
  \let\@oddhead\@oddh  \let\@evenhead\@evnh
  \let\@oddfoot\@oddf  \let\@evenfoot\@evnf
  \markboth{}{}
 }

\def\entry[#1#2]
 {\ifthenelse{\equal{\lastchar}{#1}}
   {}
   {\ifthenelse{\boolean{first}}
     {\setboolean{first}{false}}
     {\end{description}}
    \renewcommand{\lastchar}{#1}
    \medskip
    \noindent\textbf{\Huge #1}
    \rule{0.9\columnwidth}{2mm}
    \begin{description}
   }
  \item[#1#2]\mark{#1#2}
 }

.
