[IREFU2]

ART. 1 . . . A substitute who desires to enter shall report to the scorer, giving his/her number.

a. Between quarters, at halftime and during a time-out, the substitute must report or be in position to report to the scorer, prior to the warning signal which is sounded 15 seconds before the end of the intermission for a 60-second time-out and prior to the 20-second warning during a 30-second time-out.
b. Substitutions between halves may be made by the substitute or a team representative.
c. During multiple free-throw personal fouls, substitutions may be made only before the final attempt in the sequence and after the final attempt has been converted.

EXCEPTION: When a player is required by rule to be replaced prior to administering the free throw(s), then all other substitutes who have legally reported may also enter the game.

See C.