What a mess - I meant to say "the 1971 NEC, not 1975".
But reading it more carefully it looks like the thread did conclude it was 1975. Had some trouble following it!
Totally beside the point, but am I misreading the thread you link to for the grounded outlets code? It looks like it's saying that was the 1975 NEC, not 1971.
You might be interested in mabiki, an infanticide practice that was most popular during the Edo period of Japan.