太好了！

/*--------------------------------------------------------------------------
  ● 獲取數據
--------------------------------------------------------------------------*/
xa=loadXML("../fictitious/Ajax/website.xml");
xn=xa.documentElement; //website根節點
var website_address=xn.getAttribute('address'); //網站根地址
var website_name=xn.getAttribute('name'); //網站名稱
io=xn.childNodes[1].childNodes;
ion=io.length;
var website_products=Array();
for (i=0;i<ion;i++) website_products[io[i].getAttribute('comment')]=io[i].getAttribute('address');
var tieba_address=website_products['貼吧'];
websiteaddress=tieba_address;

現在各二級域名都能調用website.xml;

http://include.blue.cat/fictitious/Ajax/website.xml

<?js

/*--------------------------------------------------------------------------
  ● 獲取數據
--------------------------------------------------------------------------*/
xa=loadXML("../fictitious/Ajax/website.xml"); //讀取虛擬目錄中的xml數據文件
xn=xa.documentElement; //website根節點
var website_address=xn.getAttribute('address'); //網站根地址
var website_name=xn.getAttribute('name'); //網站名稱
io=xn.childNodes[1].childNodes; //產品目錄
ion=io.length; //產品數量
var website_products=Array();
for (i=0;i<ion;i++) website_products[io[i].getAttribute('comment')]=io[i].getAttribute('address'); //循環遍歷各產品
var tieba_address=website_products['貼吧'];
websiteaddress=tieba_address;

?>