letter stampings, my yellow (maybe orange) is stamped as show here.

While I will verify tonight, I do believe that these scans show two different chips. The reverse sides do not have the stampings.

I believe that the intent of the stamping was meant to be "FV" and the scan on the left shows a poor stamping of the "F" which was re-done above the bad one. However, I am only fairly certain that the letter stamp is of the letter "F". It could be the letter "E" making the initials "EV".

FYI, I have posted these scans previously.

Also, I do believe that these letter stampings were done with commonly available metal stamps, as opposed to hot-stamping.