Starrett made these things in two versions, one where the body and other attachments were hardened and the other wasn't. The hardened one had a smooth glossy finish and the soft one had a crinkle finish. I think your is the hardened version, Dan. If it is, that's the good one! Both used a hardened and tempered blade.
I never thought that a square would be calibrated on a regular basis. Is that typical?
-frank