Subject: Date attributes

From: Walter Underwood <[email-masked]>
Date: Thu, 29 Jul 2004 16:46:29 -0700

This is not about which dates we allow: issued, modified, whatever.

We've dropped a couple of issues:

1. Dates with an unknown timezone. We know these are in the
   LiveJournal database, and they may be elsewhere.
2. Author preference for how the date is expressed. This is not
   localization, this is part of the author's creative expression.

Provide an attribute to signal that the time zone is unknown.
Use the string inside the element for the optional, author-preferred
format. No string means no author preference.

<date.munged clock-timezone-unknown='true'
  date='2004-07-29T13:01:00-00:00'>Sol 90 of Mars Spirit Rover
Mission</date.munged>

<date.unmunged date='2004-07-29T13:02:00+00:00'/>

wunder
--
Walter Underwood
Principal Architect, Verity

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From: Sam Ruby <[email-masked]>
Date: Thu, 29 Jul 2004 21:06:51 -0400

>  date='2004-07-29T13:01:00-00:00'>Sol 90 of Mars Spirit Rover

If you look at ISO 8601[1], section 5.3.1, you will see that there is a 
syntax for defining local times: one simply omits the time zone information.

Another reference worth reading is in the XML Schema Part 2: 
Datatypes[2].  Note for those that have an allergy to XML Schema in 
general: what vocabularies such as RelaxNG are based on XML Schema Part 
2... it is XML Schema Part 1 that is controversial.

If we decide to pursue an author preference for expression (to be 
honest, I'm ambivalent on this), I'd prefer that this be in a "title" 
attribute.  Combining these two together, the example above would look 
like this:

<date.munged title="Sol 90 of Mars Spirit Rover 
Mission">2004-07-29T13:01:00</date.munged>

- Sam Ruby

[1] http://lists.ebxml.org/archives/ebxml-core/200104/pdf00005.pdf
[2] http://www.w3.org/TR/xmlschema-2/#dateTime

---

From: Walter Underwood <[email-masked]>
Date: Thu, 29 Jul 2004 18:21:34 -0700

--On Thursday, July 29, 2004 9:06 PM -0400 Sam Ruby <[email-masked]> wrote:
> If we decide to pursue an author preference for expression (to be honest,
> I'm ambivalent on this), I'd prefer that this be in a "title" attribute.
> Combining these two together, the example above would look like this:
>
> <date.munged title="Sol 90 of Mars Spirit Rover Mission">2004-07-29T13:01:00</date.munged>

I put it in the content because we've been leaning toward leaving room
for markup within text. There is no way we can allow markup within the
ISO 8601 date.

> syntax for defining local times: one simply omits the time zone information.

I'll check it out, but we've been settling on a very limited subset
of ISO 8601, and I fully agree with that. Even though things are
legitimately published on "2004-07", that is a royal pain for clients.

wunder

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From: Sam Ruby <[email-masked]>
Date: Thu, 29 Jul 2004 21:48:43 -0400

> legitimately published on "2004-07", that is a royal pain for clients.

Agreed.  I fully support the notion of a limited subset.  RFC 3339 looks 
really good, though for interoperability I would prefer to not take 
advange of the following:

       NOTE: ISO 8601 defines date and time separated by "T".
       Applications using this syntax may choose, for the sake of
       readability, to specify a full-date and full-time separated by
       (say) a space character.

And I'm mildly concerned about the following:

       NOTE: Per [ABNF] and ISO8601, the "T" and "Z" characters in this
       syntax may alternatively be lower case "t" or "z" respectively.

But my real point is that if we see a valid requirement the need to 
express local times without offsets, then we should consider widening 
the profile *slightly* (i.e., making the offset optional) instead of 
introducing the following as an attribute:

       clock-timezone-unknown='true'

- Sam Ruby

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From: Walter Underwood <[email-masked]>
Date: Fri, 30 Jul 2004 12:32:04 -0700

--On Thursday, July 29, 2004 9:06 PM -0400 Sam Ruby <[email-masked]> wrote:
> Another reference worth reading is in the XML Schema Part 2: Datatypes[2].

Excellent. Let's do that. The XML Schema document is also clear
about how to compare local times with unknown time zone, in section
"3.2.7.3 Order relation on dateTime". That should be normative
for Atom.

Should local times should be allowed when publishing entries?
We need them in feeds and archiving, because of older databases,
but can we forbid them for new content?

wunder