[tei-council] <when>/@absolute and dateTime values

[Syd Bauman]

I think your analysis is pretty correct, although I reach a slightly
different conclusion.

* The "BST" is leftover from P4, when it was specified in the
  absolute=. I don't know how it got dropped. Seems to me the value
  of absolute= in that example in TS should have been 12:20:01+01:00.

* While you're right, and in many cases the note in data.temporal.w3c
  is right, in many (if not most) cases where we can imagine
  <timeline> being used, dates (and for that matter time zones) are
  simply irrelevant. In many (if not most) cases, although the times
  might be compared, they're only going to be compared to other
  <when> in the same timeline, or other <timeline>s in the same
  corpus. Thus requiring a date (IMHO) would be silly.

So my first reaction is that think we should drop the "BST", and
re-iterate the warning that if you expect the values in your timeline
to be compared to other values out there in the world, you should
include a date and timezone.

> This bit of Chapter 8:
> 
> <http://www.tei-c.org/release/doc/tei-p5-doc/en/html/TS.html#TSSAPA>
> 
> contains this example:
> 
> <timeline unit="s" origin="#TS-P1">
>   <when xml:id="TS-P1" absolute="12:20:01"/>
>   <when xml:id="TS-P2" interval="4.5" since="#TS-P1"/>
>   <when xml:id="TS-P6"/>
>   <when xml:id="TS-P3" interval="1.5" since="#TS-P6"/>
> </timeline>
> 
> with the following commentary:
> 
> "... TS-P1 is located absolutely, at 12:20:01:01 BST. TS-P2 is 4.5 
> seconds later than TS-P2 (i.e. at 12:20:46)..."
> 
> I was first of all puzzled by the assertion that this is BST (British
> Summer Time). Nothing in the example suggests that there is any
> timezone offset from UTC, which I assumed was the default. Then I
> looked at the datatype for @absolute, which is data.temporal.w3c,
> about which we say in a note:
> 
> "If it is likely that the value used is to be compared with another, 
> then a time zone indicator should always be included, and only the 
> dateTime representation should be used."
> 
> <http://www.tei-c.org/release/doc/tei-p5-doc/en/html/ref-data.temporal.w3c.html>
> 
> So in this context, the xsd:dateTime representation should be used,
> and it should include a timezone. So I looked at the W3C spec:
> 
> <http://www.w3.org/TR/xmlschema-2/#dateTime>
> 
> which, as I read it, requires the presence of a date; whereas our 
> example has only a time.
> 
> It seems to me, therefore, that this usage of @absolute is wrong on
> two counts: first, it should include a date, and second, it ought to
> have a timezone offset of 'Z', the canonical representation for an
> offset of zero, i.e. UTC. Further, I think the claim that this value
> is BST makes no sense (BST is UTC+1) given that the example has no
> timezone offset in it.
> 
> Am I missing anything here?