function checklist(element_id)
{
	counter = 0;
	resume = true;
	while(resume==true)
	{
		checkbox = document.getElementById(element_id + '_' + counter);
		if (checkbox!=null)
		{
			if (checkbox.checked==true)
				checkbox.checked = false;
			else if (checkbox.checked==false)
				checkbox.checked = true;
		}
		else
			resume = false;
		counter++;
	}
}