The README is a bit misleading because there is no mention of the 16 "reserved" bytes. I suggest to change this part:
ABBBBCCCCCCDDD…DDD(EEE…EEE)
to something like
ABBBBCCCCCCCCRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRDDD…DDD(EEE…EEE)
I've only been working with API V3 so far but I guess V1 and V2 are similar?