Date/time on the Internet
misha.wolf at reuters.com
Wed Jun 18 18:58:53 UTC 1997
Increasing numbers of Internet-related protocols and standards need to
reference dates/times in a standard manner. The base standard mostly used for
this purpose is [ISO 8601]. This agreement on one base standard is a Good
A note for folks working with dates where YYYY < 0000 or YYYY > 9999:
I know ISO 8601 isn't right for you. You'll need to use another standard
which fits your requirement. Sorry.
ISO 8610 is a *very* permissive standard and so each Internet-related
protocol/standard is making up its own profile of ISO 8601. That is a Bad
Thing. Some of these are conformant profiles; others are not. And that's a
Very Bad Thing. Some of the profiles are more restrictive; others are less so.
An example of a non-conformant profile is that used by PICS 1.1
[REC-PICS-labels-961031]; see the extract below. This profile is
non-conformant in that it separates the YYYY and MM and DD portions using the
character "." instead of "-". The PICS profile is also surprisingly
restrictive, in that it does not permit seconds to be included.
An example of a conformant profile is that used by
[draft-newman-datetime-01.txt]. This profile is also rather restrictive for
some Internet-related protocols and standards, in that it mandates the use of
hours, minutes and seconds. Some users may wish to specify only a date when
creating metadata. Chris has agreed to make the time portion optional in his
I would suggest we need a single profile which is:
- widely adopted,
- easy to understand,
- not too permissive,
- not too restrictive,
- electronically available.
We also need to persuade the people specifying forthcoming standards such as
PICS-NG, Cougar, etc, to use this profile.
So, how do we proceed? Chris Newman's Internet Draft has two further
disadvantages: (i) it's an Internet Draft (rather than an RFC) and (ii) it is
made rather large and intimidating by catering for dates/times in the future
and the associated mish-mash (did I spell that right?) of time zones. One
possibility would be for Chris, who is currently busy on other important stuff,
to find the time to split his Internet Draft into two: (i) a quickie covering
just a profile of ISO 8601 and (ii) another, covering the more complex stuff.
Another possibility would be for someone else to do the job (I'm not
A note on distribution: I have not found a single suitable forum for this
topic, so I suggest it be discussed on the open lists (meta2 at mrrl.lut.ac.uk)
and (www-html at w3.org) and request that you send your responses to those two
lists. I'll forward this initial message to a few other relevant lists,
mostly closed ones, to give people on those lists notice of this thread.
[ISO 8601] "Data elements and interchange formats -- Information interchange --
Representation of dates and times", ISO 8601:1988(E), International
Organization for Standardization, June, 1988.
[REC-PICS-labels-961031] "PICS Label Distribution Label Syntax and
Communication Protocols", Version 1.1, W3C Recommendation 31-October-96.
[draft-newman-datetime-01.txt] "Date and Time on the Internet", Chris Newman,
Internet Draft, January 1997.
An extract from [REC-PICS-labels-961031] follows:
quoted-ISO-date :: '"'YYYY'.'MM'.'DD'T'hh':'mmStz'"'
based on the ISO 8601:1988 date and time standard, restricted
to the specific form described here:
YYYY :: four-digit year
MM :: two-digit month (01=January, etc.)
DD :: two-digit day of month (01 through 31)
hh :: two digits of hour (00 through 23) (am/pm NOT allowed)
mm :: two digits of minute (00 through 60)
S :: sign of time zone offset from UTC ('+' or '-')
tz :: four digit amount of offset from UTC
(e.g., 1512 means 15 hours and 12 minutes)
For example, "1994.11.05T08:15-0500" is a valid quoted-ISO-date
denoting November 5, 1994, 8:15 am, US Eastern Standard Time
Note: The ISO standard allows considerably greater
flexibility than that described here. PICS requires precisely
the syntax described here -- neither the time nor the time zone may
be omitted, none of the alternate formats are permitted, and
the punctuation must be as specified here.
Misha Wolf Email: misha.wolf at reuters.com 85 Fleet Street
Standards Manager Voice: +44 171 542 6722 London EC4P 4AJ
Reuters Limited Fax : +44 171 542 8314 UK
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