var m =0;

function pdmenu(x){

 if(document.getElementById){

  if(m!=0 && m==x){
   document.getElementById(m).style.visibility = "hidden";
   m=0;
  }
  else{
   if(m!=0){
    document.getElementById(m).style.visibility = "hidden";
   }
   document.getElementById(x).style.visibility = "visible";
   m=x;
  }
 }

 else if(document.all){
  if(m!=0 && m==x){
   document.all(m).style.visibility = "hidden";
   m=0;
  }
  else{
   if(m!=0){
    document.all(m).style.visibility = "hidden";
   }
   document.all(x).style.visibility = "visible";
   m=x;
  }
 }
}