function entree(){
 if (history.length==0) return true;
 if (document.referrer=="") return true;
 return (document.referrer.indexOf(document.location.hostname)==-1);
}

function fin(){
 return (false);
}

function debut(){
 return entree();
}

function initHistory(){
 if (entree()) window.location.replace();
}

function precedente(){
  if (!debut()) window.history.back();
}
function suivante(){
  if (!fin()) window.history.forward();
}

function initInterface(){
// if (entree()) document.images['preced'].src=location.protocol+'//'+location.host+'/allieres/images/interface/prec.jpg';
}