what does that means ? I allways wonder

 

Date it was cast,core box (mold),etc...

 

Care to elaborate on the castings?

 

A lot of stuff that's made in a mold has those. Look at battery cases, the have em too, on the bottom usually. I work in a machine shop now, but I always used to wonder that too. The molds have small dials with number that you can actually turn to set at a certain date.