THE WORLD'S LARGEST WEB DEVELOPER SITE

XML 教程

XML主页 XML简介 XML使用方法 XML Tree XML语法 XML元素 XML属性 XML命名空间 XML显示 XML HttpRequest XML解析器 XML DOM XML XPath XML XSLT XML XQuery XML XLink XML验证器 XML DTD XML模式 XML服务器 XML 示例 XML 测试 XML 证书

XML AJAX

AJAX简介 AJAX XMLHttp AJAX请求 AJAX响应 AJAX XML文件 AJAX PHP AJAX ASP AJAX数据库 AJAX应用程序 AJAX 示例

XML DOM

DOM简介归纳 DOM节点 DOM访问 DOM节点信息 DOM节点列表 DOM遍历 DOM导航 DOM获取价值 DOM变更节点 DOM删除节点 DOM替换节点 DOM创建节点 DOM添加节点 DOM克隆节点 DOM 示例

XPath 教程

XPath简介 XPath节点 XPath语法 XPath轴 XPath运算子 XPath 示例

XSLT 教程

XSLT简介 XSL语言 XSLT转换 XSLT <template> XSLT <value-of> XSLT <for-each> XSLT <sort> XSLT <if> XSLT <choose> XSLT申请 客户端上的XSLT 服务器上的XSLT XSLT编辑XML XSLT 示例

XQuery 教程

XQuery简介 XQuery示例 XQuery FLWOR XQuery HTML XQuery条款 XQuery语法 XQuery添加 XQuery选择 XQuery函数

XML DTD

DTD简介 DTD构建基块 DTD元素 DTD属性 DTD元素 vs Attr DTD实体 DTD 示例

XSD Schema

XSD简介 XSD如何 XSD <schema> XSD元素 XSD属性 XSD限制

XSD Complex

XSD元素 XSD Empty XSD元素 Only 仅限XSD文字 XSD混合 XSD指标 XSD <any> XSD <anyAttribute> XSD替代 XSD示例

XSD Data

XSD字串 XSD日期 XSD数值 XSD杂项 XSD 参考

Web Services

XML服务 XML WSDL XML SOAP XML RDF XML RSS

参考

DOM节点类型 DOM节点 DOM节点List DOM NamedNodeMap DOM文档 DOM元素 DOM属性 DOM文字 DOM CDATA DOM评论 DOM XMLHttpRequest DOM解析器 XSLT元素 XSLT / XPath函数

DTD Tutorial


What is a DTD?

A DTD is a Document Type Definition.

A DTD defines the structure and the legal elements and attributes of an XML document.


Why Use a DTD?

With a DTD, independent groups of people can agree on a standard DTD for interchanging data.

An application can use a DTD to verify that XML data is valid.


An Internal DTD Declaration

If the DTD is declared inside the XML file, it must be wrapped inside the <!DOCTYPE> definition:

XML document with an internal DTD

<?xml version="1.0"?>
<!DOCTYPE note [
<!ELEMENT note (to,from,heading,body)>
<!ELEMENT to (#PCDATA)>
<!ELEMENT from (#PCDATA)>
<!ELEMENT heading (#PCDATA)>
<!ELEMENT body (#PCDATA)>
]>
<note>
<to>Tove</to>
<from>Jani</from>
<heading>Reminder</heading>
<body>Don't forget me this weekend</body>
</note>
View XML file »

In the XML file, select "view source" to view the DTD.

The DTD above is interpreted like this:

  • !DOCTYPE note defines that the root element of this document is note
  • !ELEMENT note defines that the note element must contain four elements: "to,from,heading,body"
  • !ELEMENT to defines the to element to be of type "#PCDATA"
  • !ELEMENT from defines the from element to be of type "#PCDATA"
  • !ELEMENT heading defines the heading element to be of type "#PCDATA"
  • !ELEMENT body defines the body element to be of type "#PCDATA"


An External DTD Declaration

If the DTD is declared in an external file, the <!DOCTYPE> definition must contain a reference to the DTD file:

XML document with a reference to an external DTD

<?xml version="1.0"?>
<!DOCTYPE note SYSTEM "note.dtd">
<note>
  <to>Tove</to>
  <from>Jani</from>
  <heading>Reminder</heading>
  <body>Don't forget me this weekend!</body>
</note>
View XML file »

And here is the file "note.dtd", which contains the DTD:

<!ELEMENT note (to,from,heading,body)>
<!ELEMENT to (#PCDATA)>
<!ELEMENT from (#PCDATA)>
<!ELEMENT heading (#PCDATA)>
<!ELEMENT body (#PCDATA)>



W3Schools is optimized for learning, testing, and training. 示例 might be simplified to improve reading and basic understanding. Tutorials, references, and examples are constantly reviewed to avoid errors, but we cannot warrant full correctness of all content. While using this site, you agree to have read and accepted our terms of use, cookie and privacy policy. Copyright 1999-2020 by Refsnes Data. All Rights Reserved.
Powered by W3.CSS.

W3Schools.com