Riverboat, that's a bit harsh.
The reason I can't remember what the Alpha bit means is because my reference books are a hundred miles away; I am a pilot stuck in a hotel room, not a controller!! I knew the answer once but it has long since vanished in my shrinking memory.
There have been annoying differences between CAP413 and MATS for many years, but I think you'll find that's not my fault. My invitation still stands for someone to elaborate on this issue, not chew my f***ing head off, to solve newcomer's query.