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Re: draft of LC comment to XML Schema WG

From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
Date: Wed, 06 Aug 2008 13:35:55 -0400 (EDT)
Message-Id: <20080806.133555.25922361.pfps@research.bell-labs.com>
To: sandro@w3.org
Cc: public-owl-wg@w3.org

From: Sandro Hawke <sandro@w3.org>
Subject: Re: draft of LC comment to XML Schema WG 
Date: Tue, 29 Jul 2008 12:39:57 -0400

> ...
> > 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 have slightly modified the proposed message, in part to respond to the
first part of your comments.

The second part is something that we probably should put in our
documents, but we don't need to burden the XML Schema WG with this, I

Received on Wednesday, 6 August 2008 17:37:09 UTC

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