15.2.2. Introduction to XML Schema

The basic knowledge you should have ¶

Before continuing, you need to have a basic understanding of the following knowledge:

• HTML / XHTML

• XML and XML namespaces

• A basic understanding of DTD

If you want to learn about these projects first, please visit 首页 Access these tutorials.

What is XML Schema? ¶

The role of XML Schema is to define legal building blocks for XML documents, similar to DTD.

XML Schema: ¶

• Define the elements that can appear in the document

• Define attributes that can appear in the document

• Define which element is a child element

• Define the order of child elements

• Define the number of child elements

• Defines whether the element is empty or can contain text

• Define data types for elements and attributes

• Define default values and fixed values for elements and attributes

XML Schema is the successor to DTD. ¶

We think XML Schema will soon replace DTD in most web applications.

The reasons are as follows: ¶

• XML Schema can be extended to meet future needs

• XML Schema is more perfect and more powerful

• XML Schema is written based on XML

• XML Schema supports data types

• XML Schema supports namespaces

XML Schema is a W3C standard ¶

XML Schema became the W3C standard on May 2, 2001.

You can find it in our W3C 教程 For more information about the XML Schema standard.