lib/HTTP/Encoder.php
public static function isBuggyIe()
    {
        if (empty($_SERVER['HTTP_USER_AGENT'])) {
            return false;
        }
        $ua = $_SERVER['HTTP_USER_AGENT'];
        // quick escape for non-IEs
        if (0 !== strpos($ua, 'Mozilla/4.0 (compatible; MSIE ')
            || false !== strpos($ua, 'Opera')) {
            return false;
        }
        // no regex = faaast
        $version = (float)substr($ua, 30);

        return self::$encodeToIe6
            ? ($version < 6 || ($version == 6 && false === strpos($ua, 'SV1')))
            : ($version < 7);
    }
public static function isBuggyIe()
    {
        if (empty($_SERVER['HTTP_USER_AGENT'])) {
            return false;
        }
        $ua = $_SERVER['HTTP_USER_AGENT'];
        // quick escape for non-IEs
        if (0 !== strpos($ua, 'Mozilla/4.0 (compatible; MSIE ')
            || false !== strpos($ua, 'Opera')) {
            return false;
        }
        // no regex = faaast
        $version = (float)substr($ua, 30);

        return self::$encodeToIe6
            ? ($version < 6 || ($version == 6 && false === strpos($ua, 'SV1')))
            : ($version < 7);
    }
public static function isBuggyIe ( ) { if ( empty ( $ _SERVER [ 'HTTP_USER_AGENT' ] ) ) { return false ; } $ ua = $ _SERVER [ 'HTTP_USER_AGENT' ] ; // quick escape for non-IEs if ( 0 !== strpos ( $ ua , 'Mozilla/4.0 (compatible; MSIE ' ) || false !== strpos ( $ ua , 'Opera' ) ) { return false ; } // no regex = faaast $ version = ( float ) substr ( $ ua , 30 ) ; return self :: $ encodeToIe6 ? ( $ version < 6 || ( $ version == 6 && false === strpos ( $ ua , 'SV1' ) ) ) : ( $ version < 7 ) ; }
Is the browser an IE version earlier than 6 SP2?

@return bool
Is the browser an IE version earlier than 6 SP2?