checked=false;
function checkedAll (reg) {
	var aa= document.getElementById('reg');
	 if (checked == false)
          {
           checked = true
          }
        else
          {
          checked = false
          }
	for (var i =0; i < aa.elements.length; i++) 
	{
	 aa.elements[i].checked = checked;
	}
      }