wa2ise,
"F"&S?
The P&S bunch have been around quite awhile as well.
Does anybody here know what the code said in the past about these non-NEMA (10A-250V) receptacles as pictured?

I'd have a big bunch of non-NEMA twistlock recps. and caps (10A-600V) if I hadn't smashed them all years ago so they wouldn't be used again.

It'd be neat if somebody could show a 10A C/B that would mate up with them....fuses, huh??...S