var InfoWin = null;

function OpenInfo (url, W, H)   {
        var WIDTH = W || 520;
        var HEIGHT = H || 450;
        var LEFT = (screen.width-WIDTH)/2;
        var TOP = 120;
        var WINFEATURE = "toolbar=no,resizable=yes,scrollbars=yes,menubar=no,status=no,left=" + LEFT + ",top=" + TOP;
        
        if (InfoWin && !InfoWin.closed) InfoWin.close();        //exist and open
        InfoWin = window.open(url, "InfoWin", "width=" + WIDTH + ",height=" + HEIGHT + ',' + WINFEATURE);
}