Yes, upon closer inspection, the "F" is actually a "P" :-) And it says "125v 15A and 250v 10A. And "UL".
The Bryant outlet IIRC came from an old electrical engineering research lab where radio and TV research was done. It provided DC 120V. One day the DC generators went down, but nobody noticed it except the maintenance staff. So they left it off thereafter, as there were no users anymore.
