You might be referring to my way of distinguishing board versions for sake of the stereo and kick harness adapter. This is not referencing any official board identifier and was done out of simplicity because there wasn’t another obvious way (from what I remember).
If someone knows the “official” version info please let me know and I will use that to avoid confusion.
Regardless, the “B” type seems to come with the factory IO board and slight shift in position of some components. The Darksoft multi works with both.