I finally received my Pilot Custom 823 <M> today and I'm super excited. Haven't been able to ink it up yet, as I'm currently at work.
So I'm spending (probably an abnormal amount of) time looking at every detail of this beautiful writing instrument.
On the nib, I understand that "14K" is the same thing as "585" (gold content) and the "15" is the nib size, but on the bottom left I see the number "115." What does it mean? A few searches didn't seem to lead me anywhere (not to say I didn't miss something).