function gel(id, from_new)
{
  if (from_new && window.opener)
  {
    if (window.opener.document.getElementById)
      return window.opener.document.getElementById(id);
    else if (window.opener.document.all)
      return window.opener.document.all[id];
  }
  else
  {
    if (document.getElementById)
      return document.getElementById(id);
    else if (document.all)
      return document.all[id];
  }
  return null;
}


function nprod(n, d)
{
  var el = gel('prod'+n, true),
      val = parseInt(el.value);

  if (isNaN(val)) val = 0;
  val += d;
  if (val > 99)   val = 99;
  if (val < 0)    val = 0;
  el.value = val;
}


function nprod2(n, d)
{
  var el = gel('prod2'+n, true),
      val = parseInt(el.value);

  if (isNaN(val)) val = 0;
  val += d;
  if (val > 99)   val = 99;
  if (val < 0)    val = 0;
  el.value = val;
}

function chk(n)
{
  var el = gel('prod'+n);
  if (isNaN(parseInt(el.value)))
  {
  el.value = val;
  }
}

function chk2(n)
{
  var el = gel('prod'+n, true);
     val = parseInt(el.value);
     el2 = gel('prod2'+n, true);

  el2.value = val;
  if (isNaN(parseInt(el.value)))
  {
  el2.value = val;
  }
}