XML documents are the class of data objects described by the XML Recommendation [XML]. All XML documents are made up of two parts:
A prolog, which, if present, contains at least the XML declaration
A body that contains the actual marked-up document
For example, the following is an XML document:
<?xml version="1.0"?> <body> content </body>
All XML documents have a logical and a physical structure. A document usually consists of a hierarchical structure of elements. An element consists of data (including null data) surrounded by start and end tags. In XML, you can generate an infinite number of custom tag sets for your documents.
Example 3-1 compares similar XML and HTML documents. HTML typically describes what a document looks ...