Must players remain on court during 30 second time-out?
Can anyone identify where this is addressed in the NFHS rule book?

The book is clear for 1 minute time-outs (Rule 5, Section 12, Art. 5) but I'll be damned if I can find the ruling for 30 second.

Thanks in advance for your comments.

You can't find it because it's not there. THe players can remain on the court, go to the bench, or, heck, get a hto dog at the concession stand, as long as they're ready to play in 30 seconds.

The first season the rule was in effect (1997-98), there was a note in the comments on the changes that said players should remain standing - the quote was something like "this is not intended to be a clipboard timeout" - but there was no penalty for sitting down.

Nothing in the rulebook covers actions during the 30-sec. However, if I had a dollar for every time I've argued over that rule or lack thereof, I'd be about $75 richer.

NCAA is explicit...
 

The NCAA rules (what we use for HS here in NY) has it explicity:

Rule 5-10, Art. 12: During a 30-second timeout, players shall stand inside the boundary line.

...and new this year:

Art. 13. During any timeout, bench personnel and players shall locate themselves inside an imaginary rectangle formed by the boundaries of the sideline (including the bench), end line, and an imaginary line
extended from the free-throw lane line nearest the bench area meeting an imaginary line extended from the coaching-box line.

There is no rule against it in HS(fed rules) though. Some states adopt the NCAA protocol, but that is their perogative.

This rule is the biggest phantom since over-the-back and his cousin reach.