RELAX NG

Namespaces, Building Blocks, and Chameleon Design

RELAX not only lets you create building blocks for inclusion into schemas, it lets you create generic building blocks that take on a namespace you specify when including those blocks into your own schemas. These generic blocks, called chameleon schemas , are designed so that they can take on the namespace of their surrounding environment.

Reexamining XHTML 2.0

Chapter 10 explored the schemas for XHTML 2.0. At the time, I told you not to worry about the namespace declarations because they hadn’t been introduced yet. It’s time to take a closer look at XHTML’s namespace usage. XHTML’s namespace declarations in the top level schema, the driver schema, are present only in the grammar element:

 <?xml version="1.0" encoding="UTF-8"?>
 <grammar ns="http://www.w3.org/2002/06/xhtml2"
         xmlns="http://relaxng.org/ns/structure/1.0"
         xmlns:x="http://www.w3.org/1999/xhtml">

  <x:h1>RELAX NG schema for XHTML 2.0</x:h1>
  .../...
    <x:h3>Structure Module</x:h3>
    <include href="xhtml-struct-2.rng"/>
   .../...
 </grammar>

What does this snippet demonstrate?

xmlns="http://relaxng.org/ns/structure/1.0"

Means that the default namespace of the schema as a XML document is http://relaxng.org/ns/structure/1.0. Translated, it means that elements without prefix in the schema as a XML document are RELAX NG patterns.

ns="http://www.w3.org/2002/06/xhtml2"

Defines the default namespace for the schema itself: the schema describes elements from the http://www.w3.org/2002/06/xhtml2 ...