I think the operative word in the 1975 code was "cover" and that was not a new change so it goes back to at least 1972. I don't have that book or anything older. Maybe Joe T does.
If there is no weather proof cover no matter how you define weather proof, it is not going to be compliant. I assume that ambiguity is how we got to the NEMA 3r standard.
Is there a label in the luminaire canopy? That would answer the question.
