function helpWindow(urlString){
    
    winH = 500;
    winW = 650;
   
    h = screen.height;
    w = screen.width; 
    
    l = parseInt((w-winW)/2);
    t = parseInt((h-winH)/2);


    window.open(urlString, "helpwin", "fullscreen=no,toolbar=no,status=no,menubar=no,scrollbars=yes,resizable=yes,directories=no,location=no,width="+winW+",height="+winH+",left="+l+",top="+t);
}