It makes sense if you think of the identifier "zero day" as a sort of birth-identity. As far as I'm aware 0day refers to having zero days of notice to fix the

It makes sense if you think of the identifier "zero day" as a sort of birth-identity. As far as I'm aware 0day refers to having zero days of notice to fix the bug. That doesn't change the day after it comes out, it's still zero days of notice.