Within a group exist many media files. These files will likely need specific handling logic to have MediaIndexer display them properly. These are known as File Handlers.
File handler definition is identical to the media group definitions. Simply define a new handler constant with the name of the class for this handler.
Figure 4.2. File Handler Definitions
define("_HANDLER_DEFAULT", "default");
define("_HANDLER_ARCHIVE", "archive");
define("_HANDLER_CODE", "code");
Each file handler class must extend the default handler class defaultHandler.