I offer my two cents on versioned terms, prompted by the 'absolutely right' 
phrasing :->.  I am firmly straddling the fence on this question.

There are multiple science users and many technical opinions that say not 
having versions is absolutely wrong.  The circumstances that could make 
'current' *not* what you want include:
- you need to understand what definition (or other statements) was in effect 
when the tag was applied
- you want to understand the transitions that the definition (or other 
statements) has undergone over time
- the meaning of a term actually is significantly different than it used to be
- additional meanings are associated with a term (e.g., an acronym is 
repurposed by another organization) at a later date

I believe the last happens much more often than your confidence suggest -- 
perhaps especially in emerging fields or those that are newly developing 
documented vocabularies, extremely advanced or subjective fields, and concepts 
that get 'culturally adopted', e.g., turned into a pejorative (slang (that last 
not our problem, for the most part).  I don't see how the exclusive use of 
non-versioned terms supports these situations.

So while I appreciate the motivations for not including versions, I think 
versions have to be offered by the system, and ideally should be used where 
unique persistent identifiers are required. 

John


On Dec 16, 2010, at 13:08, Jeff deLaBeaujardiere wrote:

> Actually, my recollection is that EPSG & OGC proposed to include version 
> numbers, and several of us argued against it and managed to convince them.  I 
> would have to dig up old emails to find out for certain who was in which 
> camp, however.
> 
> Regards,
> Jeff DLB
> 
> On 2010-12-16 15:57, Lowry, Roy K. wrote:
>> Hi Jeff,
>> 
>> It's interesting to see the difference of opinion between the standards 
>> developers (the idea of version number in URI came from the OGC URN 
>> specification: interesting how EPSG came to a different conclusion) and 
>> those who have to live with the consequences. The more I think about it, the 
>> more I think you and Benno are absolutely right.
>> 
>> Cheers, Roy.
>> ________________________________________
>> From: [email protected] [[email protected]] On 
>> Behalf Of Jeff deLaBeaujardiere [[email protected]]
>> Sent: 16 December 2010 19:40
>> To: John Graybeal
>> Cc: [email protected]
>> Subject: Re: [CF-metadata] Web reference to a standard name?
>> 
>> On 2010-12-14 12:56, John Graybeal wrote:
>>> Just to be crystal clear, the places where you have '16' could also have 
>>> 'current' (if I understand correctly what Roy was saying about their 
>>> server), and the mmisw one could also be served with a particular version 
>>> ID (analogous to the NERC example).
>> 
>> I think it is of the utmost importance to have a URI that does not include a 
>> version number
>> and always provides the latest answer. Otherwise you have a proliferation of 
>> identifiers
>> mean the same thing but appear to change every time the overall vocabulary 
>> is updated. You
>> can also have a version-specific entry if desired.
>> 
>> There were similar discussions regarding identifiers for coordinate 
>> reference system
>> identifiers from EPSG (European Petroleum Survey Group), and it was 
>> fortunately
>> recognized that a version-less URI was essential.
>> 
>> -Jeff
>> 
>> 
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John Graybeal   <mailto:[email protected]> 
phone: 858-534-2162
System Development Manager
Ocean Observatories Initiative Cyberinfrastructure Project: 
http://ci.oceanobservatories.org
Marine Metadata Interoperability Project: http://marinemetadata.org   

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