XML Pocket Reference, 3rd Edition

A Simple XML Document

If you’re new to XML or just need to identify a feature you haven’t seen before, looking at a sample document may be helpful. The document shown in Example 1-1 contains a variety of XML features.

Example 1-1. A simple XML document

1  <?xml version="1.0" encoding="UTF-8" standalone="no" ?>
2  <?xml-stylesheet href="mine.css" type="text/css" ?>
3  <!--This is a very simple document.-->
4  <!DOCTYPE message SYSTEM "myMessage.dtd" >
5  <message xmlns="http://simonstl.com/ns/examples/message"
6              xmlns:xsi="http://www.w3.org/2001/XMLSchema-
               instance"
7              xsi:schemaLocation="message.xsd"
8              xml:lang="en" date="2005-10-06" >
9        This is a message!
10  </message>

This document contains many common XML structures, each of which is described briefly here and in greater detail later in this book. Line 1 is an optional XML declaration that provides version and encoding information, plus a declaration that indicates whether or not the document stands alone (i.e., whether it relies on external markup declarations). Line 2 is a processing instruction—more precisely, an XML stylesheet processing instruction that references a local CSS stylesheet. Line 3 is a comment and line 4 is a document type declaration (or DOCTYPE declaration) that points to a document type definition, or DTD. A DTD contains rules for document validation. The message element start-tag, on line 5, is the root (or document) element. This element contains several attributes with varying purposes. The attribute on line 5 ...