On 22/02/11 23:23, Bill Seymour wrote:
I had trouble understanding this as well, so I wrote a little paper about it, mostly for my own benefit:
http://www.cstdbill.com/tzdb/tz-how-to.html
I've mentioned it a couple of other times on this list, and nobody has corrected me yet. 8-)
Looks good. It'd be great if this (or something like it) could be distributed with tzcode.
I think that much of the confusion is due to the rules wanting to be /both/ transitions (most of the rule) /and/ steady states (the SAVE and LETTER columns). I give an example in the paper.
Zones are definitely steady states. My understanding is that they're in effect during the half-open interval, [previous line's UNTIL, this line's UNTIL). If there's no previous line, the lower bound is the beginning of time; for the last line, which has no UNTIL, the upper bound is the end of time. 8-)
Does that make sense?
--Bill
It makes sense to me. -- -=( Ian Abbott @ MEV Ltd. E-mail: <abbotti@mev.co.uk> )=- -=( Tel: +44 (0)161 477 1898 FAX: +44 (0)161 718 3587 )=-