\documentclass{beamer}

\def\lang{@LANG}
\def\file{@FILE}
\def\dirschema{@DIRSCHEMA}
\def\dirdoc{@DIRDOC}
\def\dircommon{\dirdoc/common}
\def\dirroot{\dirdoc/\lang}


% Package de variables d'environnement : Titre, command etc ...
\usepackage{Include/ppt-style}
\include{Package/\file}
\usepackage{Package/\file}

%------------------------------------------------------------------------------
% Début document
%------------------------------------------------------------------------------

\begin{document}

%Slide de Titre
\frame{\titlepage}

\section{Plan}

\frame
{
  \tableofcontents
}


%------------------------------------------------------------------------------
% Ajout du corps du documents
%------------------------------------------------------------------------------

\input{\dirroot/root}

%------------------------------------------------------------------------------
% Fin d'ajout du corps du document
%------------------------------------------------------------------------------

\end{document}