So I AR as much as I center referee so I'll list some of the things center referees have asked me to do when I AR and some things that I have asked them. This may be a long list and definitely not discussed at every match, but some things that I remember discussing are below.
1. All balls out for a throw in on your half is your call. Feel free to signal immediately.
2. All balls out on my side, feel free to give me your advice by doing a "low half signal" and then mirror my call. A "half signal" is basically putting the flag straight down along the leg matching the direction of the throw in and then raise it a few inches away from your leg.
3. Your first and most important responsibility is offside. Always stay with the 2nd to last defender or the ball, whichever is closest to the goal line - the offside line.
4. Get your butt to the goal line so you are in position to see if the entire ball crosses the goal line for a goal, corner, or goal kick. If it's ever close, feel free to give a subtle/discreet hand signal (like a thumbs up) indicating the ball is in play. This applies to throw ins too.
5. If the ball crossed the touch line or the goal line and you aren't sure of direction or the call, raise your flag to indicate that the ball went out and just look at me. I'll understand that you aren't sure and then you can mirror my decision. Just make sure you signal the ball went out.
6. If you think it's a corner kick, don't signal from where you are standing and move down the line with your arm dangling. Jog to the corner flag, turn and make eye contact with me, and signal. Just jogging to the flag tells me you think it's a corner. It's give me a second to think in case it was close and we will signal together or you can follow my signal.
7. Signal a goal kick from where ever you are standing and then move to be even with the goal box.
8. When running down the line, say on a through ball, keep your flag straight down so it's not waving and distracting the center referee.
9. If there is a through ball and it is NOT obvious that the attacker chasing the ball is onside, give a subtle/discreet hand signal.
10. Discuss fouls in your area. Remember to give direction if you signal for a foul.
11. Discuss fouls in the penalty area. Some referees are ok with you calling fouls outside the penalty area but not inside.
12. Discuss substitutions and how they are to be handled. Where I am, there are ALOT of different leagues with many didn't rules and procedures. Also, sometimes you are facing away from the team benches when subs step up so you may ask the AR2 to mirror the substitution signal when AR1 is signaling for subs.
13. Discuss offside. Some center referees like the flag raised early, some center referees want you to run down the line until the attacker plays the ball. Etc. Or the other way around, if you don't talk about it, some ARs raise their flag earlier than you'd like or vice versa...especially if there was touch by the defender on the way through.
14. Discuss foul throws. Some center referees want full authority. Some give the AR full authority. Some will want the AR to watch the feet and he'll watch the throw. Etc.
15. Discuss handballs. As we know, they can be subjective and some center referees do not want ARs calling any handballs unless it's super obvious and they were screened or something.
Lastly, yes, there is a lot of information in the back of the book for AR positioning, etc. Anyway...here are some things that you may or may not want to discuss at some point.
