substitution

[Loudwhistle2]

We had a meeting last night and the question came up about substitute A1 that has legally entered the game during a dead ball. I argued that A1 could be subbed out during that same dead ball period without playing a tick. Other reffs disagreed, I believe I'm correct and I'm sure I've read that subs don't have to play a tick. When I was asked for proof I just said I read it on the forum. Can anyone direct me to the correct rule. We dug through all the subbing rules with no luck.

Thanks