var subs_array = new Array("sub1","sub2","sub3","sub4","sub5");
function displaySubs(the_sub){
        if (document.getElementById(the_sub).style.display==""){
        document.getElementById(the_sub).style.display = "none";return
  }
  for (i=0;i<subs_array.length;i++){
        var my_sub = document.getElementById(subs_array[i]);
        my_sub.style.display = "none";
        }
  document.getElementById(the_sub).style.display = "";
  }