// retrieve XML document (reusable generic function);
// parameter is URL string (relative or complete) to
// an .xml file whose Content-Type is a valid XML
// type, such as text/xml; XML source must be from
// same domain as HTML file
function loadXMLDoc(url) {
	// branch for native XMLHttpRequest object
	if (window.XMLHttpRequest) {
		req = new XMLHttpRequest();
		req.onreadystatechange = processReqChange;
		req.open("GET", url, true);
		req.send(null);
	// branch for IE/Windows ActiveX version
	} else if (window.ActiveXObject) {
		isIE = true;
		req = new ActiveXObject("Microsoft.XMLHTTP");
		if (req) {
			req.onreadystatechange = processReqChange;
			req.open("GET", url, true);
			req.send();
		}
	}
}


// retrieve text of an XML document element, including
// elements using namespaces
function getElementTextNS(prefix, local, parentElem, index) {
	var result = "";
	if (prefix && isIE) {
		// IE/Windows way of handling namespaces
		result = parentElem.getElementsByTagName(prefix + ":" + local)[index];
	} else {
		// the namespace versions of this method 
		// (getElementsByTagNameNS()) operate
		// differently in Safari and Mozilla, but both
		// return value with just local name, provided 
		// there aren't conflicts with non-namespace element
		// names
		result = parentElem.getElementsByTagName(local)[index];
	}
	if (result) {
		// get text, accounting for possible
		// whitespace (carriage return) text nodes 
		if (result.childNodes.length > 1) {
			return result.childNodes[1].nodeValue;
		} else {
			return result.firstChild.nodeValue;			
		}
	} else {
		return "n/a";
	}
}