Since our local so-called NFL football team was "blacked out" locally, due to a lack of interest, I decided to listen to the weekly butt kicking on the radio and make productive use my free time working on a Rogers Dayton-era bass drum I purchased over the week-end. My plan was to remove all the hardware from the shell for the purpose of giving the lugs, claws and t-rods a thorough cleaning. I could listen to the "sitcom" while actually getting something done!

While working on the t-rods, I noticed that engraved on the underside of the "T" is the following: "Y.I." to the left of the T and "1" to the right; or "Y.I." to the left of the T and "2" to the right.

Anyone know what these markings indicate?

THANKS!