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. I haven't BeOS under my hands then I can't test. If you have an other answer for that function let us know. A+ Jerome