从 DTDs 转换到 XML Schemas 时元素和属性的变化 DTD XML Schema

<!ELEMENT ROOT (A,B) >

<element name="ROOT">

 <complexType content="elementOnly">

  <element ref="t:A">

  <element ref="t:B">

 </complexType>

<element>

<!ELEMENT ROOT (A|B) >

<element name="ROOT">

 <complexType content="elementOnly">

  <choice>

   <element ref="t:A">

   <element ref="t:B">

  </choice>

 </complexType>

<element>

<!ELEMENT ROOT (A|(B,C)) >

<element name="ROOT">

 <complexType content="elementOnly">

  <choice>

   <element ref="t:A">

   <sequence>

    <element ref="t:B">

    <element ref="t:C">

   </sequence>

  </choice>

 </complexType>

<element>

<!ELEMENT ROOT (A?,B+,C*) >

<element name="ROOT">

 <complexType content="elementOnly">

  <element ref="t:A" minOccurs="0">

  <element ref="t:B" maxOccurs="unbounded">

  <element ref="t:C" minOccurs="0" maxOccurs="unbounded">

 </complexType>

<element>

DTD XML Schema

<!ATTLIST ROOT

    a CDATA #REQUIRED>

<element name="ROOT">

 <complexType content="elementOnly">

  <attribute name="a" type="string" use="required"/>

 </complexType>

<element>

<!ATTLIST ROOT

    a CDATA #IMPLIED>

<element name="ROOT">

 <complexType content="elementOnly">

  <attribute name="a" type="string" use="optional"/>

 </complexType>

<element>

<!ATTLIST ROOT

    a (x|y|z) #REQUIRED;>

<element name="ROOT">

 <complexType content="elementOnly">

  <attribute name="a">

   <simpleType base="string">

    <enumeration value="x"/>

    <enumeration value="y"/>

    <enumeration value="z"/>

   </simpleType>

  </attribute>

 </complexType>

<element>

<!ATTLIST ROOT

    a CDATA #FIXED "x">

<element name="ROOT">

 <complexType content="elementOnly">

  <attribute name="a" type="string" use="fixed" value="x"/>

 </complexType>

<element>