What are the positions "CA", "TK", and "AP"? The credits for each episode of Kowabon feature credits for the positions "CA", "TK", and "AP". For example, from episode 11:



What are these positions? The official website for Kowabon doesn't list these positions on its staff page, and I don't believe I've seen them in the credits of any other anime I've watched. (With these being two-letter acronyms, I have no idea how to search for them effectively.)

I suspect that they might have something to do with Kowabon being rotoscoped (note: the topmost position in the screenshot above is "cameraman", which is something you're only likely to find when rotoscoping is involved). Though, then again, I had a look at the credits of an episode of Aku no Hana, and didn't see these particular positions credited (though they could've been there under some other name).
I didn't know about kowabon, but In general.

CA: Camera assistant.
TK: Time keeper. (who check length of script that match to scene.)
AP: Assistant producer.  

Evidence:
CA is positioned next to カメラマン"Camera Man".
TK is positioned next to 音声"Voice"
AP is positioned to last.