No clue, huh? How about if you see the business end:
Well, if you know that the bar is an inch wide (very exactly: 1.000) and half an inch tall (ditto: 0.500), you at least have a sense of scale. Yes, they are letters, and yes, they are both reversed and upside-down. So, if you hold your monitor upside down in front of a mirror, you'll see it says, "GSG". It's a Grant Street Garage stamp!