[Marklarkin]

NFHS Rule 5-8-2d

We all know that the horn is information only for substitution purposes, and we have a specific procedure we go through to allow substitutes to enter the game.

We also tell players to ignore horns when the ball is live. It is not the responsibility of the players to judge the status of the ball at the end of the period, or when there could have been an inadvertant horn.

The horn is information that time has run out of the quarter. Officials determine if there is any foul/violation/tap/try that has to be judged on before the quarter actually ends.

Since players are conditioned to stop play when they hear a whistle, the responsible official should sound their whistle to get the players attention to prevent further/unecessary play.

Also sounding your whistle right away and waving off a tap or try provides immediate information of your ruling.