On the R32 there is a wear "guide"....dont know how to explain it, but there is a piece of metal, like the metal shim on the back of the pad, that as the pad wears comes in contact with the rotor.
Basically its there to make a squeal noise as the pad gets low (mine had heaps left) to make sure u check ur brakes in the near future. (who wouldn't if they were squealing??
I just removed the wheel, seen there was heaps left, then bent this little wear idicator back a bit to give less warning.
Sorry if its different, but its on the r32, and me mates brothers n13 pulsar.