XSD:如何正确使用从抽象类型派生的类型元素?

List 类型。

<?xml version="1.0" encoding="utf-8"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">

  <xs:complexType name="BaseListContent" abstract="true" />

  <xs:complexType name="BaseList" abstract="true">
    <xs:sequence>
      <xs:element name="id" type="xs:int" />
      <xs:element name="content" type="BaseListContent" />
    </xs:sequence>
  </xs:complexType>

  <xs:complexType name="ListContent">
    <xs:complexContent>
      <xs:extension base="BaseListContent">
        <xs:sequence>
          <xs:element name="id" type="xs:int" minOccurs="0" maxOccurs="10" />
        </xs:sequence>
      </xs:extension>
    </xs:complexContent>
  </xs:complexType>

  <xs:complexType name="List">
    <xs:complexContent>
      <xs:extension base="BaseList">
        <xs:sequence>
          <xs:element name="content" type="ListContent" />
        </xs:sequence>
      </xs:extension>
    </xs:complexContent>
  </xs:complexType>

  <xs:element name="list" type="List" />

</xs:schema>

现在,我尝试根据架构验证以下XML文档:

<list>
  <id>1</id>
  <content>
    <id>1</id>
    <id>2</id>
  </content>
</list>

但是 告诉我文档无效:

> xmllint --noout --schema ~/test.xsd ~/test.xml
test.xml:1: element list: Schemas validity error : Element 'list': Missing child element(s). Expected is ( content ).
test.xml fails to validate

content ?

更新:更新版本的 xmllint公司 (使用libxml版本20904)显示架构中的错误。

$ xmllint --noout --schema test.xsd test.xml
test.xml:3: element content: Schemas validity error : Element 'content': The type definition is abstract.
test.xml:1: element list: Schemas validity error : Element 'list': Missing child element(s). Expected is ( content ).
test.xml fails to validate