Roots of the DTD

Ron Bourret rbourret at dvs1.informatik.tu-darmstadt.de
Fri Jun 5 11:57:08 BST 1998


Toby Speight wrote:

> Peter> At 17:27 04/06/98 -0400, John Cowan wrote:
> 
> >> Hmmm.  This sounds like the "root" (my syntax) or "RootElement"
> >> (Ron's syntax) attribute in XSchema is a Bad Thing.  Perhaps it
> >> should be removed?
> 
> Peter> Yup :-). I have not commented on the current proposals because
> Peter> I wanted them to anneal before public comment. *For describing
> Peter> a DTD*, here should be no requirement to define a <root> of any
> Peter> sort, only <element>, <attribute>, <contentSpec> and possibly
> Peter> <entity> and <notation> according to how people think.
> 
> I can forsee applications where one might say, "Please send me documents
> conforming to the FOO schema," in much the same way as one requests
> LaTeX or Word formats these days.  In which case, one usually needs also
> to specify the root element (this is implied in LaTeX or Word).  I don't
> see any harm in the schema having a default root (on the understanding
> that documents may, if they wish, use a different root).

A default root might fly.  Certainly a mandatory root is wrong.

In many ways, the XSchema PI is like DOCTYPE -- it points to a document 
containing the structure of your document.  As Simon suggested, it should 
therefore have a way to specify the root element, similar to the doc-type in the 
DOCTYPE declaration.

Unfortunately, these raises conflicts between DOCTYPE and the XSchema PI, since 
they are two different ways to do the same thing.  For example:

<!DOCTYPE a SYSTEM "myxschema.xsc">  // root element is a

<?XSchema myxschema.xsc a>           // root element is a

<!DOCTYPE a>
<?XSchema myxschema.xsc>             // root element is a

<!DOCTYPE a>
<?XSchema myxschema.xsc b>           // root element is ???

<!DOCTYPE a SYSTEM "myxschema.xsc">
<?XSchema yourxschema.xsc b>         // ?????

I don't like telling people they can use DOCTYPE or XSchema PIs but not both.  I 
also don't like having to write a long list of conflict resolutions -- it just 
makes XSchemas harder to use.  In both cases, it feels like we are imposing 
requirements not in the XML spec.  Ideas?

-- Ron Bourret

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