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

[Paul Eggert]

On 5/19/21 4:35 PM, Kerry Shetline wrote:
> Can you show me an example of what the format of a three-mode set of data would look like?

I doubt it. I don't think we've ever done it. If we were to do it (I 
hope not), we'd probably have to change ziguard.awk to implement it.

There may be an expectation here that the vanguard/main/rearguard 
formats are well-specified. They're not. They're purely a hack, they're 
implemented only by ziguard.awk, we don't even need vanguard any more, 
and I hope the need for rearguard goes away as well. Perhaps in the 
future we'll need to do this sort of delayed-implementation again; when 
that happens we may do it in an entirely different way.