[tz] Zone ID in binary (was Re: Version in zoneinfo files?)

Hmm... are the coordinates shown in the zone.tab file stable enough to use as IDs? If so, then a geohash of the relevant point would be a reasonable choice that would fit in the 15 future bytes. Suitable schemes that come to mind are Geohash-36, a base-64 variant of the base-32 geohash.org scheme, or (if we wish to be a bit less obfuscatory) Maidenhead locators. And some other provisions for non-geographic zones. More detailed analysis to follow when I'm at my full-powered computer. Envoyé de mon iPhone