I cannot recall the example given in NEMA SM23.However, resolution of Forces and Moments from one point to another in space follows simple laws of vector . Forces when moved carries a couple wth it, moments go as is as they are free vectors. That is all and nothing else. It does not matter what NM23 or ano other document says as ultimalely it is vector algebra which governs. What SM 23 tells ( and may be having multiple interpretations) is about the resolution point.This may be at the intersection of shaft and exhaust nozzle axis or at the center of the exhaust nozzle.Beyond this, it is vector algebra .

Regards