The distances are by the color of the stake.
Blue 50yds max
Orange 50yds max
Green 45yds max
Yellow 35yds max
White 25 yrds max

Best bet would be to go to www.ibo.net and have a good read of the rules it is all defined in there.

In all classes if the range captain wants to be sneaky he will have targets from a few feet out to the max yardage.