When is an attribute an attribute?

[Tim Bray]

At 10:35 AM 07/04/98 -0700, Rich Koehler wrote:
>I've become fond of the method that Tim Bray used to distinguish between
>elements and attributes in his discussion of MCF
>(http://www.textuality.com/mcf/MCF-tutorial.html).  He writes, "...when
>the property has a simple value like a string, we put that in the
>content of the element; when the property's value is another object, we
>put a pointer to it in an attribute value 

Hmm, recommendations do come back to haunt one.  I guess I'd
sign up for part of that statement - putting URL^HIs in attribute
values rather than element content seems to be a basic part of Web
culture, and has come to feel natural.

But I'm on the record as saying I've never heard a convincing universal
decision procedure for what should be an element and what an attribute.
There are *some* things where it's easy - if you need further internal
structure, use an element, for example.  But my beliefs on this are:

1. I have observed that humans doing document design are comfortable
   with having two ways of labeling content, and assign things to 
   elements or attributes for reasons that seem good to them.
2. It is often the case, after designers have done this, that they 
   change their minds.  I know I do.
3. For all of these reasons, if software needs to extract information
   from XML documents, it should be prepared to extract it either
   from character data or from attribute values, and not struggle
   against what the designer decided.
 -Tim


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