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Re: reference needed - w3.org versioned documents

From: Tim Berners-Lee <timbl@w3.org>
Date: Fri, 4 Apr 2008 15:30:22 -0400
Cc: Pat Hayes <phayes@ihmc.us>, www-tag@w3.org WG <www-tag@w3.org>
Message-Id: <7A6A479D-F27B-486F-A915-C4E938514546@w3.org>
To: Jonathan Rees <jar@creativecommons.org>

On 2008-03 -31, at 08:40, Jonathan Rees wrote:

> Actually I was just trying to find an example of a URI for a  
> document for which there was explicit *justification* in using the  
> URI to name the document.  The question is not so much about any  
> server "giving" any particular response, as about whether when the  
> URI is used in an assertion, will anyone will understand what was  
> meant by the URI. (Server behavior factors into any assessment of  
> this, but is not definitive, as servers can behave inscrutibly,  
> unpredictably, or incorrectly.) I think one would be hard pressed to  
> find any intelligent, diligent person aware of the w3.org URI policy  
> statement thinking that the dated URI refers to anything other than  
> that particular document (version). The other URI, however, is open  
> to many interpretations - maybe it names different things at  
> different times (maybe you have to know when the use of the URI was  
> written in order to be able to understand assertions using the URI),

No.

> or maybe it names a Fieldingesque "resource" (a time-varying  
> membership-of-representation-in-something function), or maybe it  
> names some particular thing whose essential properties can be  
> communicated,

Yes, where that thing changes with time. Pat is right.

> or maybe it names a network endpoint.

No, that is a level error.  The network endpoint is under the hood.

> In any of these interpretations there is little guidance in knowing  
> *which* thing of whatever variety is being named.

On the contrary, apart from many years of use by w3.org and many other  
web sites, there is for example my now aging http://www.w3.org/DesignIssues/Generic 
  and the ontology http//www.w3.org/2006/gen/ont.

> In other words, the URI is not of much use as a name at the present  
> time.

I take exception to that remark.  People use these usefully all the  
time.

>
> I'm not arguing for or against any particular meaning for the  
> undated URI - just observing that (as everyone in this list knows)  
> there is no consensus.

Wrong.  I think actually there is a strong tradition of using these  
URIs in a way which has been generally understood by everyone  
involved. Even though there is no philosophical discussion, or  
mathematical definition, such URIs have been very useful, and their  
has been a shared understanding about how they work.

It is not useful to try to pick hole in a system by claiming things

> To me the question is not "what does the URI mean" but "how will the  
> URI help us to communicate among ourselves and why". Our best hope  
> for being able to use the undated URI as a name would be a credible  
> statement from w3.org permitting, enabling, and encouraging us to  
> use it in some particular way, as it has made for the dated URI.


There are corner cases, where for example one can argue as to whether  
the latest version of CSS 2 is CSS 2.0.9 or CSS 2.1  -- but that is  
splitting hairs. The principles involved and the usefulness of a  
"latest version" link are, I think, well established.

> Jonathan
>
> On Mar 29, 2008, at 8:47 PM, Pat Hayes wrote:
>> At 4:28 PM -0400 3/28/08, Jonathan Rees wrote:
>>> Could someone please point me to the memo that explains the naming  
>>> policy used by w3.org that prescribes that dereferencing
>>>      http://www.w3.org/TR/2003/WD-rdf-mt-20030123/
>>> always gives the same thing but
>>>     http://www.w3.org/TR/rdf-mt/
>>> might not?
>>
>> I believe the rationale is that both of them give the "same thing",  
>> but different things. The dated URI always gives you the version of  
>> the publication which was published on the date in question. The  
>> undated URI always gives you the version of the publication which  
>> is most current on the date you de-reference the URI. You might say  
>> that the first gives you a dated draft, the second gives you the  
>> actual publication. Actual publication are entities that are  
>> themselves, of course, subject to change: but the change is not in  
>> the reference mapping from the URI to the publication, but in the  
>> publication itself. The very same publication might look different  
>> on one date from how it looks on another, c.f. a blog or a newspaper.
>>
>> I am pretty sure that this is indeed explained in a W3C note  
>> somewhere, but I can't get hold of it right at present.
>>
>> Pat
>>
>>> Thanks
>>> Jonathan
>>
>>
>> -- 
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>
Received on Friday, 4 April 2008 19:30:56 GMT

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