function invertir(theelement)
   {
	   theform = document.aspnetForm;
	   for (i=0;i<theform.elements.length;i++)
	   {
		   if (theform.elements[i].type == "checkbox")
		   {
			   if (theform.elements[i].name != theelement)
			   {
				   theform.elements[i].checked = false;
			   }
			   else
			   {
				   theform.elements[i].checked = true;
			   }
		   }
	   }
   }	

	function SeleccionarTodo(theelement)
	{
		theform = document.aspnetForm;
		var chkTog;
		for (i=0;i<theform.elements.length;i++)
		{
			if (theform.elements[i].type == "checkbox")
			{
				if (theform.elements[i].name == theelement) 
				{
				   chkTog = theform.elements[i];
               break;				   
				}
			}
		}
		for (i=0;i<theform.elements.length;i++)
		{
			if (theform.elements[i].type == "checkbox")
			{
				if (theform.elements[i].name != theelement) 
				{
					theform.elements[i].checked = chkTog.checked;
				}
			}
		}
	}