Hi,
Have not figure out what MSG_TYPE_CHANGED, MSG_DISCOVER, and MSG_UPDATE (#15, #1025, #1026) are used for yet.
MSG_TYPE_CHANGED is used for "Multi Frontend" tuners, eg. upcoming DVB-C/T combi for DM500HD.
If your hardware supports several frontend types (which might not be true in your case), you can register them, so that the user can choose the frontend to use from enigma2.
The other two messages are introduced by the application.
Roland