Re: about vs. ID

From: Peter F. Patel-Schneider (
Date: 01/09/01

I agree with Pat.  If there is no meaningful difference between about= and
ID=, then there should be clear communication to that effect.


From: pat hayes <>
Subject: Re: about vs. ID
Date: Tue, 9 Jan 2001 11:55:32 -0800

> Mike Dean wrote:
> >My opinion (written before Frank's latest message):
> >
> >I used only about= in most of the DAML I've generated, but
> >have come to believe that ID= is the preferred idiom
> >(especially for Classes and Properties).  ID= simplifies
> >the naming issues and signals the author's intent that this
> >is the "primary" definition of the object.  Conversely,
> >about= signals the author's intent that he is making an
> >assertion about "someone else's" object.
> I think this gets to the heart of the issue. Is such an 'intent' 
> actually meaningful in the language? Does it have any semantic 
> content? If not, then it is probably a mistake to give users the 
> impression that they are signalling something that they are in fact 
> not saying, even if it makes them feel better.  Either they should be 
> told clearly that the apparent distinction isnt in fact a meaningful 
> distinction, or else the language should be modified so that the 
> distinction they want to make is in fact reflected in the semantics 
> somewhere.
> >Two IDs can exist for a given URI only in the same page.  A
> >DAML Validator should issue a warning if multiple IDs exist
> >for the same name.  It should also probably suggest that
> >
> >  about="#name"
> >
> >be replaced with
> >
> >  ID="name"
> >
> >I think DAML+OIL should continue to support both ID= and
> >about= and that "best practice" should encourage the
> >appropriate use of both.
> As I understand the situation, there isnt an appropriate use for both 
> right now, since they mean the same thing.
> Pat
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