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   Re: [xml-dev] Who can implement W3C XML Schema ?

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> From: noah_mendelsohn@us.ibm.com
> All of us who worked on the schema specification understand the difficulty
> of reading the specification.  We are and have been very concerned about
> it.
> Anyway, the other problem is that the specification is difficult to read.
> I can assure everyone that we struggled mightily and iterated many times
> to make it more accessible.  It's easy to say "this should be easier to
> read", it's much harder to make it both easier to read and truly rigorous.
>  I would welcome a concrete fragment that shows how to do this.

The last time this issue came up on xml-dev, I gave a number of concrete
examples of ways I thought the language could be improved. To quote from
that email:

"Contributing to the problem are big words, run-on sentences, and lack
of flow. For example, the following sentence is a pretty representative
example. (I chose it because I thought I had a chance of rewriting it.)

   Except for anonymous complex type definitions (those with
   no {name}), since type definitions (i.e. both simple and
   complex type definitions taken together) must be uniquely
   identified within an XML Schema, no complex type definition
   can have the same name as another simple or complex type

This could be rewritten as:

   If a type definition has a name (that is, it has a <i>name</i>
   property), that name must be unique within a given XML Schema.
   Simple and complex type definitions share the same space for
   such names. That is, a simple type and a complex type cannot
   have the same name.

or even the following, although it risks unclarity with respect to
simple and complex types having the same name:

   No two type definitions (whether simple or complex) in an XML
   Schema can have the same name."

Now, it's possible that I have introduced errors in my rewrite -- I just
noticed that the original restricts the names of complex types only,
while my rewrite restricts the names of both simple and complex types --
but I think the basic language is vastly easier to understand and shows
what can be done.

Please note that I'm aware of how big a job rewriting a spec of this
size is. I only keep bringing it up because I believe it is possible and
the scope for improvement is substantial enough to be worth the effort.

-- Ron

[1] http://lists.xml.org/archives/xml-dev/200010/msg00357.html


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