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TIFF and LibTiff Mail List Archive

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2022.05.12 18:42 "[Tiff] best tiff tag names for start and end datetimes?", by Simon (Vsevolod) Ilyushchenko
2022.05.12 18:53 "Re: [Tiff] best tiff tag names for start and end datetimes?", by Kemp Watson
2022.05.12 18:59 "Re: [Tiff] best tiff tag names for start and end datetimes?", by Simon (Vsevolod) Ilyushchenko
2022.05.12 19:13 "Re: [Tiff] best tiff tag names for start and end datetimes?", by Kemp Watson
2022.05.12 19:16 "Re: [Tiff] best tiff tag names for start and end datetimes?", by Even Rouault
2022.05.12 19:25 "Re: [Tiff] best tiff tag names for start and end datetimes?", by Kemp Watson
2022.05.12 19:45 "Re: [Tiff] best tiff tag names for start and end datetimes?", by Bob Friesenhahn
2022.05.12 20:09 "Re: [Tiff] best tiff tag names for start and end datetimes?", by Simon (Vsevolod) Ilyushchenko
2022.05.12 21:50 "Re: [Tiff] best tiff tag names for start and end datetimes?", by Even Rouault
2022.05.12 21:58 "Re: [Tiff] best tiff tag names for start and end datetimes?", by Simon (Vsevolod) Ilyushchenko
2022.05.12 22:15 "Re: [Tiff] best tiff tag names for start and end datetimes?", by Even Rouault
2022.05.12 22:29 "Re: [Tiff] best tiff tag names for start and end datetimes?", by Kemp Watson
2022.05.12 23:34 "Re: [Tiff] best tiff tag names for start and end datetimes?", by Simon (Vsevolod) Ilyushchenko
2022.05.13 00:35 "Re: [Tiff] best tiff tag names for start and end datetimes?", by Leonard Rosenthol
2022.05.13 00:18 "Re: [Tiff] best tiff tag names for start and end datetimes?", by Julian H. Stacey

2022.05.13 00:18 "Re: [Tiff] best tiff tag names for start and end datetimes?", by Julian H. Stacey

1. Bob: The reason I'd like to have the option of timezones is that modern timestrings like ISO8601 often have them, so using Z to indicate UTC (which is indeed the majority of our timestamps) would both handle the common case and allow the possibility of using other timezones.

When I last read bits of 8601, I can't recall it allowing textual names of TZ, I hope not. https://en.wikipedia.org/wiki/ISO_8601#Usage

Best avoid any TZ scheme that allows textual names for local timezones, Insist on numeric only. I once wrote C to make sense of dates in mail headers,

http://www.berklix.com/~jhs/src/bsd/jhs/bin/public/mailname/mailname.c

It was a pain, needing extensions as I discovered more acronyms.

Then I wondered about the world of politicians who muck around changing whether & when they will change dates of summer / winter shifts this year, or go double summer time, or suppress summer time & stick to winter / solar, or lock permanently on a 1 hour summer offset, & that for every nation on earth, & regions within some contries, & eg I recall Australia used to have 3 x 40 min shifts across the Nullabor.

All the ever changing timezone complexity is dealt with eg in FreeBSD in special libraries, & most likely different libraries on other BSD & Linuses, so a porting hastle.

Best avoid porting or maintenace work by insisting on numeric only date strings (+ 'Z' & '-' & ':' ).

Simon (Vsevolod) Ilyushchenko wrote:

> Unix type systems (and those using NTP) have a system clock which is
> on UTC time.

Long ago I had a BSD 4.2 binary kernel whose native time was PDT=GMT-7

http://www.berklix.com/~jhs/symmetric/

I think numerous really old Unix binary kernels did. It would seem risky assuming all modern commercial binary kernels use UTC? even if the modern PD src/ BSD & Linux may.

Cheers,

Julian Stacey http://berklix.com/jhs/ http://stolenVotes.uk
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