> I search in the BeBook the IsPersistent function and that > point me to the same function from the class BVolume I > what I understood this function return if the media can > be disconnected and then I think the BMidiEndpoint::IsPersistent > return the same kind of info. That return true if the > BMidiEndpoint are hardware published from a drivers. That is what I thought too. I just ran a simple test but none of the driver endpoints on my system are persistent. They all return false from IsPersistent(). Just to be sure, I also looked up the documentation on BVolume, but it does not really say that the media can be disconnected. BVolume::IsPersistent() determines whether the data stays on the volume, after a reboot, for example. A RAM-disk would not be persistent, because the data is lost when the computer is turned off. A floppy disk or a harddrive _are_ persistent, because they retain their data. Maybe that is what BMidiEndpoint::IsPersistent means: that the MIDI data does not disappear. If that is so, an endpoint that reads from a Standard MIDI file, for example, would be persistent. But maybe the function simply is not used for anything at all, right now. I don't know. Matthijs