var xmlHttp;
    function createXMLHttp()
    {
        if(window.XMLHttpRequest)
        {
            xmlHttp=new XMLHttpRequest();
        }
        else
        {
            xmlHttp=new ActiveXObject("Microsoft.XMLHTTP");
        }
    }
    function findSubTypes(tid)
    {
        createXMLHttp();
        xmlHttp.open("POST","ProductServlet?status=findbytypes&tid="+tid);
        xmlHttp.onreadystatechange=findSubTypesCallBack;
        xmlHttp.send(null);
        
    }
    function findSubTypesCallBack()
    {
        if(xmlHttp.readyState==4&&xmlHttp.status==200)
        {
            var allSubTypes=xmlHttp.responseXML.getElementsByTagName("subtypes")[0].childNodes;
            var select=document.getElementById("subtypes");
            select.length=1;
            select.options[0].selected=true;
            for(var i=0;i<allSubTypes.length;i++)
            {
                var subtype=allSubTypes[i];
                var option=document.createElement("option");    
                var stid=subtype.getElementsByTagName("stid")[0].firstChild.nodeValue;
                var title=subtype.getElementsByTagName("title")[0].firstChild.nodeValue;                                                                  
                option.setAttribute("value",stid);
                option.appendChild(document.createTextNode(title));
                select.appendChild(option);                
            }            
        }
    }