$data['media'] – The id for the called file
$data['file'] – The filename of the file about to be delivered, can be modified by your plugin
$data['mime'] – The Mime-Type of the file, can be modified by your plugin
$data['download'] – Whether the file is to be downloaded or displayed inline
$data['cache'] – The wanted cache behavior (-1 = cache forever, 0 = never cache, >0 cache time in seconds), can be modified by your plugin
$data['ext'] – Extension of the file
$data['width'] – Images only: the wanted width as specified in the request
$data['height'] – Images only: the wanted height as specified in the request
$data['status'] – The current status code of the request
$data['statusmessage'] – The status message corresponding to the status above