If this is in a shop, I would imaging that they measure wear based on the standard width of your brake pads and then input how much is missing (worn).
So wear would start at 0 and go to whatever the width is (probably something like 16/32 or so)
So your brake pads would be at half life with 8/32 wear.
"If it's not broke, your not trying"
2000 TJ, 3.5" RE Superflex lift, 1" coil spacers in front, 35" Mickey Thompson MTZs, 9500lb winch, Super 30/35 front/rear e-lockers, newly re-installed (and straightned) HD Rugged Ridge tierod and draglink
Card carrying member of Team Red. Or would be if we had cards.....