Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Posting-Version: version B 2.10.1 6/24/83; site watmath.UUCP
Path: utzoo!watmath!ljdickey
From: ljdickey@watmath.UUCP
Newsgroups: net.news,net.mail
Subject: What time is it?
Message-ID: <5699@watmath.UUCP>
Date: Mon, 5-Sep-83 16:54:48 EDT
Article-I.D.: watmath.5699
Posted: Mon Sep  5 16:54:48 1983
Date-Received: Tue, 6-Sep-83 02:20:27 EDT
Sender: ljdickey@watmath.UUCP
Organization: U of Waterloo, Ontario
Lines: 57

I noticed recently a problem that was experienced by someone receiving
messages apparently before it was sent (the dreaded "BST" problem:
British Summer Time, Bering Strait Time).  It seems clear that there is
no way to resolve this problem by introducing local interpretations to
such symbols that everybody's mail program is supposed to understand.
Our net is "coming of age" now, and we need to adjust to the problem of
a regional net (that started out largely North American) growing into
one that is worldwide.

Other nets have experienced and faced up to this problem, and have come
repeatedly to the same solution, namely that the only sensible thing to
do is to use just ONE time that everybody understands.  One notable
recent example is the Sharp APL Timesharing Service which is based in
Toronto, but which serves users in far flung places.  They use a date
and time system based on Coordinated Universal Time (what used to be
called Greenwich Mean Time).

I propose that we adopt the notion of a time stamp for our messages
(mail and news) that gives the date and time in an international
standard format.  It is not expected that any user will ever have to
read that format, but it will be decipherable.  When the user sends a
message, an "SIDate:" line is included: the date that is included is
the SI (International Standard) date and time (Greenwich Mean Time).
When any other user reads the message the date and time will be printed
according to whatever time has been chosen for that site.

For example, if it is 2:35 in the afternoon, Eastern Daylight Savings
Time on the 5th of September (where I am), the SIDate line would be
something like:

	   SIDate: 1983 09 05 18:35:19
or
	   SIDate: 1983 09 05  18 35 19

and there would be no other designation such as EDT or Mon.  A reader
of that message who is at a site on the west coast of North America
would be given a date like

	   Date: Mon, Sep. 5 11:35 A.M.

which would be the time it was there when the message was sent.
Similarly, a user in Britain might get a date message like

	   Date: Mon, Sep. 5  7:35 P.M.

Because that is the time and date, as calculated by the mail program,
assuming that it is British Summer Time, when the message was sent.

Note that at each site there need be only two kinds of conversions:
one from the current local time to GMT and one that is the inverse.  No
site has to know about the time convention that is used at any other
site.
-- 
	Lee Dickey		(ljdickey@watmath.UUCP)
				...!allegra!watmath!ljdickey
				...!ucbvax/decvax!watmath!ljdickey
				University of Waterloo