var XML = new Object();
/**
 * Create a new Document object. If no arguments are specified,
 * the document will be empty. If a root tag is specified, the document
 * will contain that single root tag. If the root tag has a namespace
 * prefix, the second argument must specify the URL that identifies the
 * namespace.
 */
XML.newDocument = function(rootTagName, namespaceURL) {
  if (!rootTagName) rootTagName = "";
  if (!namespaceURL) namespaceURL = "";
  if (document.implementation && document.implementation.createDocument) {
    // This is the W3C standard way to do it
    return document.implementation.createDocument(namespaceURL, rootTagName, null);
  }
  else { // This is the IE way to do it
    // Create an empty document as an ActiveX object
    // If there is no root element, this is all we have to do
    var doc = new ActiveXObject("MSXML2.DOMDocument");
    // If there is a root tag, initialize the document
    if (rootTagName) {
      // Look for a namespace prefix
      var prefix = "";
      var tagname = rootTagName;
      var p = rootTagName.indexOf(':');
      if (p != -1) {
        prefix = rootTagName.substring(0, p);
        tagname = rootTagName.substring(p+1);
      }
      // If we have a namespace, we must have a namespace prefix
      // If we don't have a namespace, we discard any prefix
      if (namespaceURL) {
        if (!prefix) prefix = "a0"; // What Firefox uses
      }
      else prefix = "";
      // Create the root element (with optional namespace) as a
      // string of text
      var text = "<" + (prefix?(prefix+":"):"") +  tagname +
          (namespaceURL
           ?(" xmlns:" + prefix + '="' + namespaceURL +'"')
           :"") +
          "/>";
      // And parse that text into the empty document
      doc.loadXML(text);
    }
    return doc;
  }
};

/**
 * Synchronously load the XML document at the specified URL and
 * return it as a Document object
 */
XML.load = function(url) {
    // Create a new document with the previously defined function
    var xmldoc = XML.newDocument();
    xmldoc.async = false;  // We want to load synchronously
    xmldoc.load(url);      // Load and parse
    return xmldoc;         // Return the document
};

/**
 * Asynchronously load and parse an XML document from the specified URL.
 * When the document is ready, pass it to the specified callback function.
 * This function returns immediately with no return value.
 */
XML.loadAsync = function(url, callback) {
    var xmldoc = XML.newDocument();
    // If we created the XML document using createDocument, use
    // onload to determine when it is loaded
    if (document.implementation && document.implementation.createDocument) {
        xmldoc.onload = function() { callback(xmldoc); };
    }
    // Otherwise, use onreadystatechange as with XMLHttpRequest
    else {
        xmldoc.onreadystatechange = function() {
            if (xmldoc.readyState == 4) callback(xmldoc);
        };
    }
    // Now go start the download and parsing
    xmldoc.load(url);
};