Re: draft of LC comment to XML Schema WG

On Tue, Jul 29, 2008 at 12:39 PM, Sandro Hawke <> wrote:
> ...
>> There are already OWL ontologies that contain dateTime values where the
>> timezone is absent.  Such dateTime values may come from different
>> documents, and that really have a different notion of what their local
>> (unspecified) time is.  The document, however, makes these values all
>> equal.
>> Our proposed solution to handling such ontologies is to put off the task
>> of determining "missing" timezones to tools, with roughly the wording
>> that tools MAY accept dateTime values with an absent timezone by
>> determining what the "local" timezone is for the value and SHOULD
>> produce a warning if they do so; otherwise dateTime values with missing
>> timezone are syntax errors.
> ...
> I find this unclear.   My understand of what the WG is saying is this:
>      It is a syntax error for an OWL 2 document to contain a dateTime
>      value (literal) which is missing timezone information.
>      Systems MAY attempt to recover from this error (such as by
>      assuming the local time zone), but if they do so, they SHOULD at
>      least notify the user.
> I would add:
>      Such "recovery" will in many cases produce incorrect (unsound)
>      results and should be done with caution, since OWL data may come
>      from unexpected contexts.  Data providers should be strongly
>      encouraged to provide data with timezone information.
>     -- Sandro
I would also suggest to mention the interval interpretation of time
without timezone as another possible way to recover (fuzzily). We
could add

     If the recover of a timezone is not possible or it likely to be
unsound, the tool may also adopt an interval-base interpretation of
datetime with missing timezone that includes all possible time values
that are compliant to the datetime value in question in any possible
timezones. A warning should be given in doing so.


Received on Tuesday, 29 July 2008 16:53:35 UTC