function filterUserInput(event)
{
	var approvedKeys= "48,49,50,51,52,53,54,55,56,57,65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,80,81,82,83,84,85,86,87,88,89,90,96,97,98,99,100,101,102,103,104,105,189";
	
	// look for the key in the approved list
	if (approvedKeys.search(event.keyCode) == -1) {
		return false;
	}
}