In [support.c.headers.other], it states that the <name.h> headers behave "as if each name placed in the standard library namespace by the corresponding header is placed within the global namespace scope". There are exceptions for several different parts of the headers, but it's left unclear as to whether or not including them in their corresponding <name.h> is optional.

Is it optional to for things such as std::byte to be included in the corresponding .h, or are they required but not put in the global namespace? The note makes it seem as if it's the former, but it's still currently ambiguous.