2nd Half - Book starters don't match who is on the court
 

Boys varsity contest the other night and the second half begins. About 30 seconds into the 3rd quarter the Home team requests a timeout because he doesn't like the matchups he has on the court. After the deadball the bookkeeper says the Home team did not start the second half with who they put in the book before the half started.

Is this a wrong starter in the book and a T is assessed?
Or
Does the 5 players become legal when the 3rd quarter begins and we play on?

Also, would this be different then the beginning of the game?

Too late to penalize.

If it's recognized before the ball becomes live, have the team put the listed starters in if they don't wnat the T (and they will always make the switch).

Unless told otherwise, don't the players who finished the 2nd quarter start the third quarter?

That's what I've always assumed, does anybody check the books before starting the second half? I don't, maybe I should?

3-3-1a Note: When a substitute is not ptoperly reported, the players in the game at the conclusion of the quarter/when the time out was called shall begin play for the new quarter/after the time out.

One of the more useless rules to be added in recent years.

Look at the players who take the floor and check them off in the book.

Yes, they are supposed to (the same as between Qs 1-2 and 3-4).

But, if they don't and the ball becomes live, it's too late to do anything.

Agreed, but how could it be a T? This isn't a situation of changing starters, so it's no more a T than if they tried it to start the 4th quarter. Unless, of course, the coach simply refused to put in the correct players. But that T would be direct on the coach for failing to comply with the officials' direction. Right?

Call In The Subs ...
 

3-3-1-A NOTE; 4-34-2: Clarified that when a substitute is not properly reported, the players in the game at the conclusion of the quarter/when the timeout was granted shall begin play for the new quarter/after the time-out. During an intermission, all team members are bench personnel for the purpose of penalizing unsporting behavior.

3-3-1-B: Substitutions between halves may be made by the substitute or a team representative.

10-2: A substitute shall not enter the court:
ART. 1 Without reporting to the scorer.
ART. 2 Without being beckoned by an official, except between quarters.
PENALTY: (Section 2) Two free throws plus ball for division-line throw-in. One
foul for either or both requirements. Penalized if discovered before the ball
becomes live.