Answer: Teams are allowed a maximum of 18 subs per set (game). Each player is permitted unlimited entries within the team limit. (Rule 10, Sec. 3, Art. 2)
Question: If an injured/ill player is properly replayed by a substitute, can that player re-enter the set?
Answer: Yes, this is a legal substitution provided he/she re-enters in the original serving order position. (Rule 10, Sec. 3, Art. 3 & 4)