function filter(u,d)
			{
				for(i=0;i<u.options.length;i++)
				{
					uid = u.options[i].value.split(':');
					did = d.split(':');
					
					u.options[i].style.display = (uid[1] != did[0] && u.options[i].value) ? 'none' : 'block';
					u.selectedIndex = 0;
					
				}
			}