<!--

        <!ELEMENT 元素(子元素,...)>

    -->

    <!ELEMENT students (student+,cat*) >

    <!ELEMENT student (name,age,sex,birth,phone*,email?,student?) ><!-- 注意元素的顺序 -->

    <!ELEMENT email EMPTY><!-- 元素里面不能包含内容 -->

    <!ELEMENT phone (#PCDATA)>

    <!ATTLIST sex value (男|女|保密) "男"><!-- 属性值可以使用枚举类型 -->

    <!--

        定义student元素的stuNo属性

        ID类型: 保证唯一性(必须由数字和字母组成)

        CDATA类型: 指定是字符串类型

        #REQUIRED 属性值是必须

        #IMPLIED  属性值是可选

    -->

    <!ATTLIST student stuNO ID #IMPLIED>

    <!ATTLIST email value CDATA #IMPLIED>

<?xml version="1.0" encoding="UTF-8" ?><!-- xml文件的声明 -->

<!DOCTYPE students SYSTEM "student.dtd"><!-- 引用外部的dtd校验文件 -->

<students>

    <student stuNO="STU0001">

        <name>关羽</name>

        <age>20</age>

        <sex>男</sex>

        <birth>1988-10-29</birth>

        <email value="guanyu@qq.com" />

        <student stuNO="SUT11001">

            <name>关羽</name>

            <age>20</age>

            <sex value="女">男</sex>

            <birth>1988-10-29</birth>

            <email value="guanyu@qq.com" />

        </student>

    </student>

    <student stuNO="STU0002">

        <name>李四</name>

        <age>20</age>

        <sex>男</sex>

        <birth>1988-10-29</birth>

        <phone>123332</phone>

        <email value="guanyu@qq.com" ></email>

    </student>

    <student stuNO="STU0003">

        <name>貂蝉</name>

        <age>20</age>

        <sex>女</sex>

        <birth>1988-10-29</birth>

        <phone>123332</phone>

        <phone>123332</phone>

        <!-- <email value="guanyu@qq.com" >fdfj</email> -->

    </student>

    <cat>

        <sex>母</sex>

        <age>3</age>

        <name>喵喵</name>

    </cat>

    <cat>

        <sex>母</sex>

        <age>3</age>

        <name>喵喵</name>

    </cat>

</students>

<?xml version="1.0"?>

<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema"

    targetNamespace="abc" xmlns="abc" elementFormDefault="qualified">

    <!-- XML Schema 缩写 当elementFormDefault="qualified" 时，所有全局元素的子元素将被以缺省方式放到目标命名空间，连同全局元素或者类型一起；

        而当elementFormDefault="unqualified" 时，所有全局元素的子元素将被以缺省方式放到无名命名空间。而属性的命名空间类似地由attributeFormDefault="？"来指明。

        需要明白的是，elementFormDefault="？" 是有作用域的，并且是被继承的，除非在子定义中覆盖父定义。 -->

    <xsd:element name="note">

        <xsd:complexType>

            <xsd:sequence>

                <xsd:element name="to">

                    <xsd:complexType mixed="true"><!-- 混合 -->

                        <xsd:sequence minOccurs="1" maxOccurs="unbounded">

                            <xsd:element name="content" type="xsd:string" />

                        </xsd:sequence>

                        <xsd:attribute name="two" type="xsd:string" use="required" />

                    </xsd:complexType>

                </xsd:element>

                <xsd:element name="from" type="xsd:string" />

                <xsd:element name="heading" type="xsd:string" />

                <xsd:element name="body" type="xsd:string" />

                <xsd:element name="age" type="xsd:integer" />

                <xsd:element name="birth" type="xsd:date" />

                <xsd:element name="sex">

                    <xsd:simpleType>

                        <xsd:restriction base="xsd:string">

                            <xsd:enumeration value="男" />

                            <xsd:enumeration value="女" />

                            <xsd:enumeration value="人妖" />

                        </xsd:restriction>

                    </xsd:simpleType>

                </xsd:element>

                <xsd:element name="weight" type="xsd:decimal" />

            </xsd:sequence>

            <xsd:attribute name="one" type="xsd:string" use="required" />

        </xsd:complexType>

    </xsd:element>

</xsd:schema>

<?xml version="1.0"  encoding="UTF-8" ?>

<note xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

      xmlns="abc"

      xsi:schemaLocation="abc note.xsd" one="属于note">

    <to two="to的属性">

        <content>fdsf</content>

        <content>fdsf</content>

        <content>fsdf</content>

    </to>

    <from>John</from>

    <heading>Reminder</heading>

    <body>Don't forget the meeting!</body>

    <age>20</age>

    <birth>1988-10-23</birth>

    <sex>人妖</sex>

    <weight>75</weight>

</note>