I asked Guy about this and he says:

------- Forwarded Message

From: guy@netapp.com (Guy Harris)
Subject: Re: Is it Daylight Savings time yet (Re: 19Mar94 current)
To: earle@isolar.Tujunga.CA.US (- Greg Earle)
Date: Tue, 29 Mar 1994 11:17:49 -0800 (PST)
In-Reply-To: <9403290925.AA17936@isolar.Tujunga.CA.US> from "Greg Earle" at Mar 29, 94 01:25:39 am
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>>I've always used "dst 5" in the kernel config and
>>/usr/share/timezone/US/Eastern and gotten the correct TOD.  However, after
>>upgrading to 19 Mar 94 binaries and building a new kernel, I'm getting TOD 1
>>hour behind.

There might be some problem with the kernel timezone stuff, which should only
be used when dealing with the time-of-day clock on a PeeCee.

Frankly, I don't think there should be *any* kernel timezone stuff, to make
damn *sure* nobody uses it.  The time-of-day clock should be dealt with by a
user-mode program, run early in the boot process, which can then use the Arthur
Olson time zone stuff.  I seem to remember being told that Linux does precisely
that ...

>On a related note, did someone pass those "Pacific-New" rules while I wasn't
>looking?
>
>On a Sun running SunOS 4.1.3, the files "PST8PDT", "localtime" and
>"US/Pacific"
>are all the same under /usr/share/lib/zoneinfo.  "US/Pacific" and
>"US/Pacific-New" are definitely different.
>
>On NetBSD, "posixrules", "US/Pacific" and "US/Pacific-New" are all the same;
>and all three are different from "PST8PDT".

"posixrules" should simply be a link to "localtime".  It is intended to supply
the DST-switching rules when TZ is set to a POSIX-style value that doesn't
incorporate the rules, e.g. "PST8PDT".  The value of the time zone offset in
"posixrules" should not make any difference (as in, one should never set TZ to
"posixrules" nor ":posixrules").

"US/Pacific" should definitely *not* be the same as "US/Pacific-New". 
"PST8PDT" should be, if:

	1) "PST8PDT" is a link to "US/Pacific";
or
	2) "posixrules" is a link to "US/Pacific"

the same as "US/Pacific".

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