ISO 8601 revision

[Markus G. Kuhn]

Keld J|rn Simonsen wrote on 1997-03-01 22:50 UTC:

[How do we get in contact with the ISO 8601 working group?]
> I can try to ask the Danish Standards people.

Great!

> Have you got any suggestions for the "ugly T"?

[Anyone interested in this discussion without a copy of ISO 8601, please
download and print first

  <ftp://ftp.informatik.uni-erlangen.de/pub/doc/ISO/ISO8601.ps.Z>

for reference.]

I think, a space is the nicest solution as in

  1997-03-01 22:50

and it should definitely be explicitely allowed. The current standard gave the
author of <http://www.internic.net/internet-drafts/draft-newman-datetime-01.txt>
the impression that the "ugly T" is the only comforming way of writing
down both date and time, which is the only reason why the new proposed
Internet standard date and time format (an ISO 8601 profile) has the "T".

Only for applications, where a space is inconvenient (e.g, Unix command line
options, where fields are separated by space), the hyphen as used in the
corresponding ANSI standard and as shown in the "Chicago Manual of Style"
is also quite nice:

  1997-02-28-22:50

I do not see, where this overloading of the hyphen would cause problems
with the requirement, that a parser must be able to distinguish all
formats. If it causes problems with unambiguous parsability, then I wouldn't
mind dropping some of the less useful notations from the ensemble.

I also find the notation "--MM-DD" awfull for cases where I do not
specify the year as it follows from context. It would be much nicer if
notations like "-MM-DD" and "-DD" would be part of the collection, as
this would allow to use these notations in sentences like

  "The conference will take place from 1997-08-28 to -31, and the
   tutorial sessions will run from -08-28 to -09-05."

Instead these patterns are currently used for "-YY" and "-YY-MM". I think,
using the leading hyphen to indicate the missing century digits was a bad
idea.

Please note that although ISO 8601 was intended as a standard for
data respresentation, it is today quoted in standards for business letter
typographical conventions (e.g., DIN 5008-1996).

ISO 8601 currently lists numerous incomplete formats which I strongly doubt
will ever be used anywhere (e.g., "---DD").  They are in applications like
Unix cron, where you want to specify periodic events, much better
represented by a more generic extended wildcard notation that allows to
specify events like the last Sunday of every month, something ISO 8601
currently does not yet provide.

Useful new notations might be

 1997-100.5   (noon of the 100th day of 1997)
 1997-02-3-7  (the third sunday of February 1997, especially useful
               with unspecified year or year/month as in
               *-3-7 or *-02-3-7)

These are just a few first ideas for improvement. Once we get in contact
with the working group and hear about their plans, we can start working
on a detailed proposal.

Markus

-- 
Markus G. Kuhn, Computer Science grad student, Purdue
University, Indiana, USA -- email: kuhn at cs.purdue.edu