RULE 15.6 SUBSTITUTIONS
The difference between 12 limited vs 12 unlimited:
Rule 15.6 illustrates the “limited rule”. For Volleyball Canada competitions, 12 “limited” substitutions are used.
In competitions that use the 12 “unlimited” substitutions, a starting player and a substitute can replace each other as in 15.6 except that they may do so more than once up to the limit of 12 substitutions within a set.
For example, #3 is a starting player and is substituted by #6. These 2 players may substitute for each other more than once up to the limit of 12 substitutions in a set - this is known as “unlimited”; however, “limited” using previous same example where #3 is a starting player and is substituted by #6. So #3 can leave the game for #6 but only once in a set, and re-enter wither same player #6 but again only once in a set.
So the difference between 12 limited and 12 unlimited is limited as defined in 15.6 per set, and unlimited is substitute more then once but up to 12 per set / game.