It is on most brands of chain. An angle bar stamped on top of the
tooth near the back. It also serves (unneeded though) as the point
you should quit filing and throw the chain away. It only give s the
top angle, on most chains the file should also be held with some "up"
angle, usually around 10 degrees.
Found my Oregon clamp on filer today. Clamped it on, and it seems to do the
deed. Can't find my manual, though, but remember enough about it to (I
think) sharpen them. Will look at that stamp tomorrow, though. The filer
was still set at the old angles, so I must have taken them off of the