function fetchOverlayDataXML(CreateOverlaysFunctionName)
{
   //method call used by AjaxServer
    var paramList = "MethodToCall=GetMarkersDataXml";
    //parameter used in AjaxServer
    var async = true;
    var method = "POST";
    getDataFromServer(requestUrl, CreateOverlaysFunctionName, async, method, paramList);
}