[cpp-threads] Visibility question

[Peter Dimov]

Nelson, Clark wrote:
>> Is my understanding correct?
>
> I'm sure that you have produced a scholarly summary of what the
> semantics of fences would/should be. However, I'm obliged to point out
> that <fence> was not actually among the atomic ordering constraints
> proposed -- at least not formally to the C++ committee in N2047.

Indeed. Is this because a <fence>-equivalent constraint (by any name) was 
contemplated, considered and rejected? I apologize for wasting bandwidth if 
so.