[tz] Vanguard vs. "main" vs. rearguard

[Paul Eggert]

On 5/20/21 10:50 AM, Kerry Shetline wrote:
> Is there a particular reason that the following situation is handled with bespoke awk processing:

The goal was to keep the data source simple, and put hacks into 
ziguard.awk when that's easy. I would rather not have these hacks bleed 
into the data source.

> It would be great if the special comments would be all one needed to parse the data for rearguard, main, or vanguard.

I see where you're coming from, but that's not the goal here. I didn't 
want to invent a preprocessor for zic, creating technology that would 
have to be documented and supported and have backwards-compatibility 
problems of its own. The vanguard/main/rearguard stuff is just a 
hopefully-temporary hack that, once it evaporates, will require zero 
maintenance.

By the way, is anybody still using rearguard format? If not, perhaps 
it's time to retire this stuff now. (That would save us all the hassle 
of conversations like this one. :-)