For the tuning exam, RPTs perform a standardized piano tuning on a piano that has been master tuned. A master tuning is one that is performed by a group of technicians until they all agree no improvements on the tuning can be made.
In the context of piano tuning exams, RPTs (presumably "Registered Piano Technicians") are required to perform a standardized tuning on pianos that have already been master tuned. This process involves a collective effort where everyone agrees there are no more adjustments needed before declaring it a master tune.