That was my first thought also but the cutout edges are at 90° with no rub marks. It's manufactured.Those cutouts were/are caused by the cable housing rubbing on something that is fairly sharp.
If I could, I would put some heatshrink with internal glue over it. More permanent than just tape.I never noticed those cut outs when I had my NT. I'd tape over them to keep any water from seeping in to the throttle cables....nothing like rust in the middle of a cable!
I was installing a longer throttle cable on a BMW800GT and remembered this thread.That was my first thought also but the cutout edges are at 90° with no rub marks. It's manufactured.