No subject
Sat Feb 25 02:52:01 UTC 2012
Status: RO
To: bostic at okeeffe.berkeley.edu,
ncifcrf!bootme.auspex.com!guy
Subject: Re: machine independence
> Speaking of
"the original ... work", how did this all get started,
> anyway?
The ultimate
impetus was the legislation that changed the start of U. S.
Daylight Saving Time
from the last Sunday in April to the first Sunday in April.
The proximate
impetus was a mod.std.unix discussion on the subject.
I've attached some of the
early electronic mail. By 1/11/86 the format
looked much as it does today. The
"hard part" not dealt with in the 1/13/86
"distribution" was the
text-format-to-binary-format converter (today's zic).
--ado
> From ado Mon Jan 6 10:28:48 1986
> To: cbosgd!mark
> Subject: Daylight
Savings Time
> Cc: seismo!philabs!linus!encore!necis!geo
> Status: O
>
> Well,
I'll admit that my first reaction to the idea of something on the order
> of
"/etc/dstcap" was a smiley face. But over the weekend I thought about the
>
matter some more. The result of the thinking was a sheet of paper with this
>
on it:
>
> > eastern:\
> > :st=EST:\
> > :dt=EDT:\
> > :os=-21000:\
>
...
> Now regardless of the way the above information is encoded, the questions
are:
> Is there enough information present above to deal with the various
>
Daylight Saving Time schemes that currently exist? Would the information be
>
enough to deal with anything that US (or foreign) legislators are likely
> to
dream up? Or does one *really* need to have something on the order of
>
"/etc/dstinfo" (with a stack and arithmetic and such)?
>
>
--ado
> >From cbosgd!cbpavo.cbosgd.ATT.UUCP!mark Fri Jan 10 16:19:08 1986
remote from seismo
> Received: from cbosgd.UUCP by seismo.CSS.GOV with UUCP;
Fri, 10 Jan 86 16:05:29 EST
> Received: from cbpavo.cbosgd.ATT.UUCP
(cbpavo.ARPA)
> by cbosgd.ATT.UUCP (4.12/UUCP-Project/11.09.85)
>
id AA17523; Fri, 10 Jan 86 15:04:29 est
> Received: by cbpavo.cbosgd.ATT.UUCP
(4.24/3.14)
> id AA03218; Fri, 10 Jan 86 15:04:20 est
> Date: Fri, 10 Jan 86
15:04:20 est
> From: seismo!cbpavo.cbosgd.ATT.UUCP!mark (Mark Horton)
>
Message-Id: <8601102004.AA03218 at cbpavo.cbosgd.ATT.UUCP>
> To: elsie!ado,
harvard!encore!encore!necis!geo
> Subject: Re: Daylight Savings Time
>
> While
I like your semantics, the format is horrible. I'd much
> prefer to see each
year (or year range) in one place rather
> than have it scattered over 14
different days of the week.
> The format has to be something the average
non-guru can understand.
> Termcap is a bit much for such people. Something
easy like
>
> Year Key Parm Time GMT offset
> 1970 3-sun
4 0200 -0400
> 1970 3-sun 10 0200 -0500
> 1971 3-sun
4 0200 -0400
> 1971 3-sun 10 0200 -0500
> 1972 3-sun
4 0200 -0400
> 1972 3-sun 10 0200 -0500
> 1973 3-sun
4 0200 -0400
> 1973 3-sun 10 0200 -0500
> 1974 julian
120 0200 -0400
> 1974 julian 306 0200 -0500
> 1975 julian
0 0200 -0400
> 1975 julian 366 0200 -0500
> 1976 3-sun
4 0200 -0400
> 1976 3-sun 10 0200 -0500
>
> This could
probably be translated into a handy binary format for ctime
> to use quickly.
The parm is either the month number (for things like
> "3rd Sunday") or the
Julian date on which to make the change. The
> above numbers are probably all
wrong but you get the idea. You could
> have any number of changes in a year,
although 2 would be common.
>
> Mark
> From ado Sat Jan 11 12:42:16
1986
> To: cbosgd!mark
> Subject: DST
> Status: O
>
> An alternate approach to
allow for multiple time zones. Make the rules look
> like:
>
> Rule
Year(s) Month Day Time ST offset String
> MostUS
-1973 Apr last-Sun 2:00 1:00 D
> MostUS -1973
Oct last-Sun 2:00 0 S
> MostUS 1974 Jan
last-Sun 2:00 1:00 D
> MostUS 1974 Nov last-Sun
2:00 0 S
> MostUS 1975 Feb last-Sun 2:00
1:00 D
> MostUS 1975 Oct last-Sun 2:00 0
S
> MostUS 1976- Apr last-Sun 2:00 1:00 D
>
MostUS 1976- Oct last-Sun 2:00 0 S
> Patron
1969- Apr last-Sun 2:00 1:00 D
> Patron 1969-
Jul last-Sun 2:00 2:00 DD
> Patron 1969- Aug
last-Sun 2:00 1:00 D
> Patron 1969- Oct last-Sun
2:00 0 S
>
> and the Time Zone information look like
>
>
Name GMT offset Rule Abbreviation
> Eastern
-5:00 MostUS E%sT
> Central -6:00 MostUS
C%sT
> Pacific -8:00 MostUS P%sT
> Alaskan
? MostUS A%sT
> Hawaiian ? MostUS
H%sT
> Patronian ? Patron P%sT
>
>
--ado
> From ado Mon Jan 13 21:04:01 1986
> To: cbosgd!mark
> Subject: The easy
part of ctime()
> Status: O
>
> The next letter from me should be a shell
archive containing five files:
> Makefile
> timezone.h
>
ctime.c
> try.c
> fake.c
> The important files are "timezone.h"
which gives the format of "binary time
> zone information files," and "ctime.c"
which makes use of the files. . .
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