// JavaScript Document
function validateZip(f) {
	var url = f.action;
	if (!isZip(f.zip.value)) {
		alert("Please enter a valid 5-digit zip code.");
		f.zip.focus();
	}
	else {
		wmdPageLink('mp-nation');
		document.location = url + "?zip=" + f.zip.value;
	}
	return false;
}
function isZip(s) {
	// Check for correct zip code
	var reZip = /^\d{5}([\-]\d{4})?$/;
	if (s == "" || s.length != 5) {
		return false;
	}
	else if (!reZip.test(s)) {
		return false;
	}
	return true;
}