I'm wondering if anyone out there has a great system of film holder coding that leaves an image number on the edge of sheet film.

All I've come up with is drilling 1/32" holes in the film flap, with the 1st hole representing the 1st digit in a 2 number code, with the 2nd series of holes being the 2nd digit. I may end up with as many as 20 holes in a flap (0-9 & 0-9)! There must be a better way!

thanks!