A customer brought me a Shamal Mille (Campagnolo wheel) in for service.

I just did a quick truing job.
The front spokes on first generation Shamal Mille wheels
have a head stamp with two parallel horizontal lines "－－",


but on the very earliest models, there's actually a slit on the nipple end
that looks like the handle of a toothpick.
Later Shamal Mille wheels and spare spokes
don't have this kind of machining.

When I first saw this, I thought
the twisting force during truing could cause micro-cracks to propagate,
and the spoke would break cleanly right at that slit.
But I've never actually seen that happen.