https://timsong-cpp.github.io/cppwp/n3337/syserr.errcondition.modifiers
[syserr.errcondition.modifiers]
modifiers
https://timsong-cpp.github.io/cppwp/n3337/syserr.errcondition.nonmembers
[syserr.errcondition.nonmembers]
nonmembers
https://timsong-cpp.github.io/cppwp/n3337/syserr.errcondition
[syserr.errcondition]