element content vs. element attribute

[David Megginson]

Ray Waldin writes:

 > In other words, when should data be contained by elements?  Or
 > conversely, when should data be an attribute of an element instead
 > of contained by that element?

Here's a good, general distinction:

* use elements for structurally-significant information; and

* use attributes for meta-data.

One problem, that will become more obvious when more XML tools are
available, is that most WYSIWYMG (M="might" or "may") XML editing
software will like show character data (element content) on the screen
by default, but will show attributes only on request, possible in a
pop-up dialog.  It makes sense to have the most important information
(the real content) inside elements, then, and to have the meta-data
out of the way in attributes.

(Peter: how do you display attributes in Jumbo?)

Of course, what is and isn't meta-data will vary depending on the
document type, but here are some common examples:

* a unique identifier
* a security level
* a revision or release level
* rendition information (yech)
* configuration information
* the preferred unit of measurement


All the best,


David

-- 
David Megginson                 ak117 at freenet.carleton.ca
Microstar Software Ltd.         dmeggins at microstar.com
      http://home.sprynet.com/sprynet/dmeggins/

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