function checkTicks(this_control) {
   
   var controlname = this_control + "[]";
   
   var chkbox = document.schform.elements[controlname];
   
   var tick_len=chkbox.length;
   
   var tick_all = true;
   
   for (var i=1;i<(tick_len);i++) {
      if (document.schform.elements[controlname][i].checked == true) {
         document.schform.elements[controlname][0].checked = false;
         tick_all = false;
         break;
      }
   }
   
   if (tick_all == true) {
      document.schform.elements[controlname][0].checked = true;
   }
}


function tickAll(this_control) {

   var controlname = this_control + "[]";
   
   var chkbox = document.schform.elements[controlname];
   
   var tick_len=chkbox.length;
   
   for (var i=1;i<(tick_len);i++) {
      if (document.schform.elements[controlname][0].checked == true) {
         document.schform.elements[controlname][i].checked = false
      }
   }
   document.schform.elements[controlname][0].checked = true;
}