[tz] [PROPOSED] date +%z now outputs -0000 for uninhabited

[Paul Eggert]

On 01/15/2017 04:57 AM, Robert Elz wrote:
> In e-mail, a zone of -0000 is intended to mean that the date/time given
> is in the sender's local time, but there is no information available about
> what that would be in UTC (no available timezone info).   It is intended for
> systems that keep only local time (if any of those remain these days.)

Yes, that's what's in RFC 5322, and it differs from what's in RFC 3339. 
The RFC 3339 interpretation is better for the more-typical case today, 
where UTC is known but local time might not be known or might be 
undefined. Also, the RFC 3339 interpretation is stricter, in the sense 
that a RFC 3339 sender of -0000 is compatible with an RFC 5322 receiver 
of -0000, whereas the reverse is not true; and this means it's better to 
use RFC 3339 when generating -0000, as is the case here.