function checkZip(z){
	if(document.images){
		z.value = z.value.replace(/\D+/, "");
	}
	if(z.value.length != 5 && z.value.length != 9){
		if(document.all || document.getElementById){
			//z.style.background = "yellow";
		}
		z.focus();
		return (false);
	}
	if(z.value.length > 5){
    z.value = z.value.substr(0,5) + "-" + z.value.substr(5);
	}
	return (z.value);
}