[tz] suggestion: split "backward" into "backward" and "deprecated"

[Paul Gilmartin]

On 2020-05-04, at 18:26:22, Andrew Gierth wrote:
> 
> I mean that where the tzcode uses "GMT" as a default zone name or
> abbreviation in the absence of data, FreeBSD uses "UTC" (and has since
> 2004).
> 
> e.g. with no /etc/localtime file,
> 
> % env -u TZ date
> Tue  5 May 2020 00:00:37 UTC
> 
> (To the best of my knowledge there are no reference clocks available to
> which one could synchronize in order to use a mean solar time, so your
> argument seems to me to support this choice.)
>  
Do you mean mean solar time at some arbitrary precise longitude
or mean solar time at the Prime Meridian?  If the latter, is
interpolated UT1 a close enough approximation?:
    https://www.nist.gov/pml/time-and-frequency-division/time-services/ut1-ntp-time-dissemination

-- gil