| <result><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></result> |