The namespace URI points to an existing directory,
http://csproj.colgate.edu/xmlp/ns/pdata/, within which the RDDL file,
index.html, is the default. The RDDL file, shown in Listing 2-10, follows this
outline:
• root element with namespace declarations
• introductory prose
• validating resources (DTD, XML Schema, RELAX NG)
• display resources (CSS)
Listing 2-10. An RDDL Example
<!DOCTYPE html PUBLIC “-//XML-DEV//DTD XHTML RDDL 1.0//EN”
“http://www.rddl.org/rddl-xhtml.dtd”>
<html xmlns=”http://www.w3.org/1999/xhtml”
xmlns:xlink=”http://www.w3.org/1999/xlink”
xmlns:rddl=”http://www.rddl.org/”>
<head><title>PData Resources</title></head><body>
<h1>PData Resources</h1>
<p>
This is a resource file for the <tt>pdata</tt> example of chapters 1 and 2 of
<cite>XML for Programmers</cite> by Alexander D. Nakhimovsky and Tom Myers.
The standard namespace for this example is
<a href=”http://csproj.colgate.edu/xmlp/ns/pdata/”>
http://csproj.colgate.edu/xmlp/ns/pdata/</a>
and that directory’s default,
<a href=”http://csproj.colgate.edu/xmlp/ns/pdata/index.html”>
http://csproj.colgate.edu/xmlp/ns/pdata/index.html</a>,
should be the URL of the current version of this file.
</p>
<h2>Validation</h2>
<p>You can validate a <tt>pdata</tt> document with a dtd,
<a href=”http://csproj.colgate.edu/xmlp/ns/pdata/pdata.dtd”>
http://csproj.colgate.edu/xmlp/ns/pdata/pdata.dtd</a>.
</p>
<rddl:resource
xlink:title=”DTD for pdata validation”
xlink:href=”http://www.csproj.colgate.edu/xmlp/ns/pdata/pdata.dtd”
xlink:role=”http://www.isi.edu/in-notes/iana/assignments/media-types/text/xml-
dtd”
xlink:arcrole=”http://www.rddl.org/purposes#validation”
>
77
Well-Formed Documents and Namespaces
