Thanks for the notes. I read the (USB) spec again page 27/28. (well multiple times) and as I understood 1 endpoint has 1 or more multiple Group Terminal Blocks for which GTB each has 1 to 16 groups (group = in/out or bi = similar to one or two midi cables/ports) per terminal block The spec I have is from May 5th, 2020. i wonder how the driver get the Function Block information function blocks are not mentioned in the USB spec. Is there a a newer USB spec? if yes, it may make no sense to develop a device now if the descriptors and USB functions calls changed. Page 28 still refers to MIDI -CI protocol negotiation which already has been removed. It's a bit confusing. Would have been better to first release the updated USB spec before releasing the updated MIDI specs.
