For the immediate question:

> I'm not quite sure what 'goback' and 'goahead' are supposed to do.

"goback" indicates that there's a 400-year pattern to the stuff at the start of the transition table that can be extrapolated backward through time; "goahead" indicates that there's a 400-year pattern to the stuff at the end that can be extrapolated forward. When a table generated from an environment variable does indeed cover 400 years, both goahead and goback should be set.

@dashdashado

On Wed, Jan 11, 2017 at 3:55 PM, Paul Eggert <eggert@cs.ucla.edu> wrote:

On 01/11/2017 11:39 AM, Arthur David Olson wrote:

> for such environment variables, in what year should application of
> daylight saving start (or should it apply to all years, no matter how
> far in the past)?

Surely it should apply to all years. POSIX doesn't require this (POSIX
specifies only behavior starting in 1970) but it would be odd for a
permanent rule to spring into action only after 1969.

The attached proposed patch does that, and fixes the problem for Kees
Dekker's case. Does this look like the right thing in general? I'm not
quite sure what 'goback' and 'goahead' are supposed to do.