Do Not Track

I am interested about this proposed HTTP HEADER.
I have another site www.comeappaio.com, in this site (only italian language, sorry) i perform some analysis on this header.
It is the latest info line… now the PHP code:

if(isset($_SERVER)) {
        $arrServer = $_SERVER;

        if(array_key_exists('HTTP_DNT', $arrServer)) {
                $value = $arrServer['HTTP_DNT'];
                if ($value == 0) {
                /* If '0', do not track */
                        $dnt_message="DO NOT TRACK DISABILITATO";  // do not track disabled
                        $dnt_value == '0';
                } else if ($value == 1)  {
                        $dnt_value = '1';
                        $dnt_message="DO NOT TRACK ABILITATO"; // do not track enabled
                } else {
                        $dnt_value = 'VALORE NON PERMESSO'; // do not track with no permitted value
                        $dnt_message="VALORE NON PERMESSO";
                }

        } else {
                $dnt_value=null;
                $dnt_message="DO NOT TRACK NON CONFIGURATO"; // do not track not configured
        }

}

Typically you will get the latest message because a lot of browser do not support do not track header….