Re: [Emailcore] Time zones

[Keith Moore <[e-mail]>]

On 8/5/22 13:59, Russ Allbery wrote:

> So*arguably*  a correct representation of an email message sent from Nepal
> in 1985 would require a non-integral minute offset to represent the local
> time zone.  In practice, this doesn't seem like something that the email
> standards should worry about, as the only relevance I can think of
> off-hand would be instructions for how to parse historic email archives
> that might contain such a message, and I'm dubious that's how the message
> would have been generated at the time.

In 1985, having a timestamp in a message that's accurate enough to need 
a non-integral minute offset for the local timezone would have been 
extremely unlikely.   So I think it's safe to say that nobody cared 
enough to try to figure out how to express a timezone offset to a 
greater degree of precision than that permitted by the then-current 
specifications, or if indeed anyone did, trying to make sense of that 
timezone representation today is a fool's errand.

But I feel like this discussion runs the danger of obscuring a much more 
important point:

NEW IMPLEMENTATIONS SHOULD NEVER TRY TO ALTER OLD MESSAGES.  Not in 
place, nor when relaying or forwarding, ideally not even when displaying 
or printing them.   Even if, perhaps especially if, the old messages 
don't conform to current specifications.

Even something as seemingly trivial as altering an obsolete timezone 
indicator in an old message can do serious harm.   For example, 
sometimes old messages are used as evidence in litigation of various 
types, or are used by historians, etc.   And the modern trend of trying 
to coerce all timezones to GMT or current local time (even if only for 
display) is also extremely damaging even if the conversion to local time 
is done correctly (which for a variety of reasons, it often isn't).   
Timezones matter, and so does the wall clock time when the message was sent.

Keith