Caroline Clewlow wrote:
> 
> The third approach seems to bear a resemblance to the reasoning behind
> object oriented approaches to programming.  i.e. re-use, 
> encapsulation, and data hiding ( namespace hiding in this case ;).  

Excellent observation.  I will note it in the online version of the Best
Practices document.

> To reflect this it may be an idea to name it the Object Design
> approach

I will mark this down as a possible name for the Third Design.
 
> The choice between the three approaches seems to again come down to 
> a style driven decision.  

Oh my, I do hope that it's not a matter of "style".  "Style" seems to
suggest "by intuition", or "by personal preference".  My hope is that we
are developing guidelines to empower a schema designer can make
intelligent decisions based upon a concrete decision space (i.e., all
the design alternatives are spelled out, and the pros and cons of each
design alternative is clearly understood).  

However, your point is well taken.  We have not clearly spelled out the
implications of the First, Second, and Third design.  Please keep us
focused until you (everyone) feel(s) comfortable that it is no longer a
"style" decision, but rather an "engineering" decision.  Thanks! /Roger