Substitution
The provision as it is printed, and everything on Ruleside that turns on it.
If there is no fourth official, the AR moves to the halfway line to assist with the substitution procedure; the referee must wait until the AR is back in position before restarting play.
Verdicts that turn on it 1
Walk the tree to any of these and this clause is part of the answer.
The Laws of the Game are published by The IFAB and quoted here for the purpose of explaining the decisions on this site. Ruleside is not affiliated with The IFAB or FIFA. Every clause of Practical guidelines for match officials that Ruleside cites.