Injurys: Whistle or not?

[DrC.]

Originally posted by tharbert
If the coach needs him in the game and you blow the whistle, he has to leave for one clock tick

For some reason I thought you could stop play to make sure everyone is OK. I thought he/she only had to go out for a tick if I beckon the Coach or Trainer onto the court. Am I wrong ??? I rather be wrong on this Forum then on the court!
Thanks...