Stumped on GD&T Position Holes Multiple Bends/Planes

[Kurtanius21]

I'm having a lot of trouble determining if the below Position callout is legitimate for or not. I've studied a lot of example positions, but there's not much literature out there for referencing datums not immediately adjacent to the position callout.

Almost all hole position callouts I've seen, the primary datum is perpendicular to the cylindrical tolerance zone. In my case, I've got a primary datum that doesn't contact the hole's cylindrical tolerance zone and is not perpendicular to it either.

I'm torn between understanding that the primary datum should be perpendicular to a hole's axis or datums can just be pictured as how you attach the part to gauges.

The position in question is the red question mark. Theoretically all degrees of freedom are covered for using datums A, B, and C. I'm picturing a flat gauge with two pins sticking out to lock the part in place. But the gauge isn't 'touching' the hole. So is that question mark position callout correct? If it is, can someone explain how it works? What is the meaning behind the datums relationship and position? (Ignore that no basic dimensions locate the holes)

 

[Garland23]

There's no rule saying that the primary datum must be perpendicular to a position tolerance zone. Datums are simply about constraining degrees of freedom, so that seems to be correct here.
My comment would be that datum C isn't needed. You've already got a pair of holes tagged as datum B, so all 6 deg. of freedom are taken care of by datums A and B.

 

[Burunduk]

The datum feature selection should usually correspond to how the part is placed in the assembly the part is going to. If it's positioned for inspection similar to the way it connects in the application, then features that are measured good will also be located and function well in the application.

You said "I'm picturing a flat gauge with two pins sticking out to lock the part in place" and that is right. So if the primary mounting feature for the assembly is also your datum feature A and the part is located and locked in rotation by two pins that stick out from the base this surface contacts, this datum choice makes sense. The two holes in question, which you are controlling relative to A, then B, then what seems to be a redundant (as mentioned by Garland) C, could be used for attaching another component, which needs to be at a certain height from the base and oriented properly.