Thanks Charlie, yes, that is correct. But it uses another track as the destination (Audio). I'm not sure then that you could multi-riff more than one track once the Audio track had already been used for a previous track's multi-riff. This is only a guess, I don't profess to really know.
The Audio Track can be converted to a Performance Track and moved to another channel so although there's only a single Audio Channel, it can be used over and over.
This process will work exceptionally well with bouncing various styles, combinations of Performance Tracks and using multiple instruments on the individual channels to create quite complex arrangements.
Because the BIAB generation engine reads ahead, BIAB does really good and accurate cross fades between the changes throughout a track.
Also, because this editing is being done digitally until rendered, there's no drops in quality of the bounces.