var canSee = 'table-row';
 if(navigator.appName.indexOf("Microsoft") > -1)
  canSee = 'block'

 function show(letter, hideall)
 {
  if(hideall) {
   alert('HIDE ALL!');
   hide_all_exhibitors();
  }
  atozname = 'atoz_'+letter;
  var exbtrlistDiv = document.getElementById('exhibitor_list');
  var trs          = exbtrlistDiv.getElementsByTagName("tr");
  for (var i=0; i<trs.length; i++) {
   if (document.getElementById) { // this is the way the standards work
    if (trs[i].id.indexOf(atozname+'') == 0) {
     trs[i].style.display = canSee;
    }
   }
  }
 }

 function hide(letter)
 {
  atozname = 'atoz_'+letter;
  var exbtrlistDiv = document.getElementById('exhibitor_list');
  var trs          = exbtrlistDiv.getElementsByTagName("tr");
  for (var i=0; i<trs.length; i++) {
   if (document.getElementById) { // this is the way the standards work
    if (trs[i].id.indexOf(atozname+'') == 0) {
     trs[i].style.display = 'none';
    }
   }
  }
 }

 function show_all_exhibitors()
 {
  var exbtrlistDiv = document.getElementById('exhibitor_list');
  var trs          = exbtrlistDiv.getElementsByTagName("tr");
  for (var i=0; i<trs.length; i++)
   if (trs[i].id.indexOf('atoz_') == 0) trs[i].style.display = canSee;
 }

 function hide_all_exhibitors()
 {
  var exbtrlistDiv = document.getElementById('exhibitor_list');
  var trs          = exbtrlistDiv.getElementsByTagName("tr");
  for (var i=0; i<trs.length; i++)
   if (trs[i].id.indexOf('atoz_') == 0) trs[i].style.display = "none";
 }