Drum vs Disc, Power vs non Power

Sure. Glad to share. I first came across the reference on a website dedicated to F*rd SHO, SHO times. Although equiped with front disks, brakes on the first generations had barely enough swept area for the heavy front weight of those cars. As a result, they often had issues with brakes getting hot, even in street use.

After some further digging, the Edge codes are a practice from the manufacturing trade group. In other words, they don't seem to be government mandated, but something the industry found helpful for themselves and maybe because the OEMs want it.

The Friction code is based on the SAE J661
The marking standard is SAE J866

First letter represents the test coefficient of friction from 0-200 F
Second letter represents test coefficient of friction from 200-600 F

To get an idea of what temperatures to expect during hard driving, the author of the SHOtimes article stated the following:
"...measured 385 F on my front rotors in rush hour traffic on a 45 mph street because of several sequential stoplights. (I have an 89 SHO with 10.1 in. rotors.)
...four back to back 60 mph stops generated 550 F."
In addition, on my Barracuda, the temperature marking paint indicates that neither the front disks (Kelsey Hayes) not the rear drums have exceded 485 degrees on the street or autocrossing. Granted the lining material and the metal that contacts it wil be a little hotter than the edges where I put the marking paint, but not a lot.

Looking through the 10x1.75" rear brake shoes I have here, the ones I can read are marked either FF or FE. Obviously FF is likely the better lined shoe if all else is equal. If someone has any OE shoes, it would be very interesting to see how they rated.
E = .25 to .35 coef. of friction
F = .35 to .45 coef of friction

As you can see there is quite a range within each letter rating. So edge codes are not the final word, but certainly useful for comparisons. It is also sometimes reveals if the lining will change grip is it gets hotter.

PS. Brake pads are marked the same way.