<result><section shorttitle="How does SGML work?">
 <title>How is SGML and would you recommend it to your grandmother?</title>
 <intro>
 <para>You can break a typical document into three layers: structure,
 content, and style. SGML works by separating these three aspects and
 deals mainly with the relationship between structure and content.</para></intro>
 <topic topicid="top4">
 <title>Structure</title>
 <para>At the heart of an SGML application is a file called the DTD, or
 Document Type Definition. The DTD sets up the structure of a document,
 much like a database schema describes the types of information it
 handles.</para>
 <para>A database schema also defines the relationships between the
 various types of data. Similarly, a DTD specifies <emph>rules</emph>
 to help ensure documents have a consistent, logical structure.</para></topic>
 <topic topicid="top5">
 <title>Content</title>
 <para>Content is the information itself. The method for identifying
 the information and its meaning within this framework is called
 <emph>tagging</emph>. Tagging must
 conform to the rules established in the DTD (see <xref xrefid="top4"/>).</para>
 <graphic graphname="tagexamp"/></topic>
 <topic topicid="top6">
 <title>Style</title>
 <para>SGML does not standardize style or other processing methods for
 information stored in SGML.</para></topic></section></result>