In an activity-on-arrow diagram

In an activity-on-arrow diagram, the nodes represent:
A work package
B activity
C dependencies
D discretionary

your views pls.

My only doubt is in PMBOK if you search for activity on arrows.. there is only one reference to it on page 246 in which there is they have not mentioned anything in detail about AOA. Are we likely to see questions like the above one, which are NOT covered in PMBOK?