In R23a it says that changing the color of any legal vex part is prohibited, but in R28 it states that Teams may label V5 11W Smart Motors (markers, stickers, paint, etc.) as long as it’s non-functional. Why?
That just serves as an exception. The primary reason for VEX creating R23a was to inhibit people buying magnesium c-channels and spray painting them to hide the fact that they were magnesium. If I mark a motor with a letter ‘B’ as my team does to mark that certain motors are working, I have in no way hidden the material that makes up my motor.
If you read R23a literally, it outlaws marking up motors for this purpose or other purposes, but VEX didn’t want to do that, so they made an exception.