What is the meaning of the PTO power transfer “standard operating speed’?

1. Correct answer: It is the RPM of the power transfer exit and of its drive shaft.
2. The RPM in which the gearbox exit shaft rotates.
3. The RPM of the oil pump that moves the power transfer.
4. The RPM of the engine itself (the “fly wheel” exit).

WhyThe PTO's standard operating speed is the RPM of the PTO output and its drive shaft, not of the engine.