I remember a lot of things that I don't need to remember, but I don't remember that in NFHS. The only change I recall was the addition of Mo' Rule back in 1982. Prior to that if a B/R player caught an airborne kick or intercept a forward pass inside their 5 yard line, stumbled and fell into the end zone it would be a safety, UNLESS,you felt the force of the ball drove the defender in= touchback. Many
officials
chose that route.
It didn't seem fair to rule it a safety.
Neither did it seem fair to rule it a touchback
.
Hence, the momentum rule was born.
Initially , the mo' rule covered airborne kicks and interceptions but was later expanded to fumbles, backward passes and the like. If a defender attempts to advance the ball after gaining possession and is brought down in the EZ the mo' still applies or touchback, if not. If the runner leaves the EZ and doesn't like what he sees and returns back in and is brought down=safety. If after COP, if B fouls in his EZ = safety under all-but-one.