Substitutes: NHSA Part 1, Q#65

[PAULK1]

JR the exceptions you are referring to are for who may shoot the FT's not for substitutions in general.
if an eligible subsitute reports he/she can enter when opportunity is there. to be ineligible you must be
1. disqualified
2. directed to leave the game for blood or injury
and try to reenter before the clock has started
3. substituted for and try to reenter before the clock has started.
4. if the subsitutes equipment or apparel is listed in 3-5
5. was unconcious without medical approval.