Example: article.xml, Part II

<section id="introduction">
<title>Introduction</title>

A Document Structure Description (DSD) is a specification of a
class of XML documents. A DSD defines a grammar for XML documents,
default element attributes and content, and documentation of the
class. A DSD is itself an XML document.  We have five major goals for the
descriptive power of DSDs, namely that they should:

<itemize>
<item>
allow context dependent descriptions of content and attributes, since
the context of a node, such as ancestors and attribute values, often
govern what is legal syntax;
</item>
<item>
generalize CSS<nbsp/><cite id="bos98:_cascad_style_sheet_css2_specif"/> 
(Cascading Style Sheets) so that readable, CSS-like rules for default attribute 
values and default content can be defined for arbitrary XML domains, not only
predefined user formatting models; 
...
</itemize>

This processing instruction has the form
<oneline>
<tt>&lt;?dsd URI="</tt><it>URI</it><tt>"?&gt;</tt>
</oneline>