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Daylight Saving Time

I hate to beat a horse which everyone wishes were dead, but:

What should DECODE-UNIVERSAL-TIME do about daylight saving time?
Clearly, ENCODE-UNIVERSAL-TIME takes it into accout, if appropriate, when
normalizing to GMT.  When decoding, however, who knows if the original time
was on daylight saving time?  And if decoding into a different time zone, who 
knows if that zone is on daylight saving time?  At the very least,
DECODE-UNIVERSAL-TIME has no business returning daylight-saving-time-p.

In VAX LISP, we take daylight saving time in account when decoding into
the local time zone, and in no other case.  This means that if a local
time is encoded and then decoded in California, it's off by one hour.
I think our algorithm is bogus, but I'm not sure what to do.

- Paul