function wop(url, wnd_name, width, height)
{
window.open(url, wnd_name, 'width=' + width + ',height=' + height + ',status=no,menubar=no,resizable=yes,scrollbars=yes,left=' + String((screen.width - width) / 2)+',top=' + String((screen.height - height) / 2));
return 0;
}