I typically see pickups slated as "P/U" and located after the take number, so, for example, you would say something like "scene 6 apple, take 3 pickup." Then "take 4 pickup," etc. I've even seen it then go back to straight "take 5," "take 6," etc. if you go back to shooting the whole take again and not just a part of it. Whatever it is, I always just defer to the Script Supervisor even if she gives you something crazy to put on the slate like (and I'm not kidding, this actually happened) "Scene X 33pt./34pt. apple, take 3 P/U." I'm not really sure what the editor made of this but as long as your getting the info on the slate that the Script Supervisor wants, then you are doing your job as a 2nd AC. I don't know why the AD tried to get involved, it's not really her concern.