function wop(url,wnd_name,width,height) {
w=window.open(url,wnd_name,'width='+width+',height='+height+',status=no,menubar=no,resizable=no,scrollbars=no,left='+String((screen.width-width)/2)+',top='+String((screen.height-height)/2));
w.document.write(''+wnd_name+'');
w.focus();
return w;
}