Re: root or document element

[James Clark <jjc@jclark.com>]

> RELAX NG does not appear to have a method for specifying a document
> element for a pattern, as does a document type declaration <!DOCTYPE
> doc-el SYSTEM "doc.dtd">,

A RELAX NG schema:

<element name="foo">
  <empty/>
</element>

is equivalent to:

<!DOCTYPE foo [
<!ELEMENT foo EMPTY>
]>

It implies a document element of "foo".  On the other hand, if I write:

<choice>
  <element name="foo">
    <empty/>
  </element>
  <element name="bar">
    <empty/>
  </element>
</choice>

Then there is not single document element: then the document element can be 
either foo or bar.

If you write RELAX NG schemas in a DTD style:

<grammar>

<start>
  <ref name="foo"/>
</start>

<define name="foo">
  <element name="foo">
    <empty/>
  </element>
</define>

<define name="bar">
  <element name="bar">
    <empty/>
  </element>
</define>

</grammar>

The the <start> element serves the role of specifying the document type 
declaration.

> nor does the RELAX NG syntax appear to require
> a document element in patterns, such as <grammar>, for processing. Would
> anyone care to express views on this?

RELAX NG does not have a single document element type.  Any element that 
specifies a pattern can be used as the document element.  For example, 
<choice> can be the document element, but <define> cannot be.

James