The logic here is that the pin(s) are assembling into holes in a mating connector. Also the points of the square pins are often spherical radii.

Alternatively, bidrectional positional tolerance could be used - this also can control clocking of the pins.

Carefully consider datum selection that is representative of what controls the location and orientation of the housings.

The answer depends on the intended usage:

1. As a secondary datum, a TOP dia callout is acceptable as long as it is fitting into a diameteral hole. Clocking in this case is not important as it will still orient itself as required for location.

2. As a tertiary datum (pin into a slot) clocking becomes important as it will cause unexcepted shifts in location if not correctly presented to the slot. I would recommend a TOP applied as 2 // planes in the critical direction.

NOTE: The above 2 scenario's are just examples of possible datum applications and are not meant to represent the only possible cases.

3. For applications where, say a square pin is fitting into a square hole, clocking of the two features becomes critical and Dave's suggestion of using the boundary function is excellent.

What I am suggesting here is to completely analyze and understand the proposed application and then apply the appropriate geometric control that will provide the desired results.