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

  <xs:simpleType name="string255">

    <xs:restriction base="xs:token">

      <xs:maxLength value="255"/>

    </xs:restriction>

  </xs:simpleType>

  <xs:simpleType name="string32">

    <xs:restriction base="xs:token">

      <xs:maxLength value="32"/>

    </xs:restriction>

  </xs:simpleType>

  <xs:simpleType name="isbn">

    <xs:restriction base="xs:unsignedLong">

      <xs:totalDigits value="10"/>

      <xs:pattern value="\d{10}"/>

    </xs:restriction>

  </xs:simpleType>

  <xs:simpleType name="bookID">

    <xs:restriction base="xs:ID">

      <xs:pattern value="b\d{10}"/>

    </xs:restriction>

  </xs:simpleType>

  <xs:simpleType name="supportedLanguages">

    <xs:restriction base="xs:language">

      <xs:enumeration value="en"/>

      <xs:enumeration value="es"/>

    </xs:restriction>

  </xs:simpleType>

  <xs:simpleType name="date">

    <xs:restriction base="xs:date">

      <xs:pattern value="[^:Z]*"/>

    </xs:restriction>

  </xs:simpleType>

  <xs:element name="name" type="string32"/>

  <xs:element name="qualification" type="string255"/>

  <xs:element name="born" type="date"/>

  <xs:element name="dead" type="date"/>

  <xs:element name="isbn" type="isbn"/>

  <xs:attribute name="id" type="xs:ID"/>

  <xs:attribute name="available" type="xs:boolean"/>

  <xs:attribute name="lang" type="supportedLanguages"/>

  <xs:complexType name="elementWithID">

    <xs:attribute ref="id"/>

  </xs:complexType>

  <xs:complexType name="bookTmp">

    <xs:complexContent>

      <xs:extension base="elementWithID">

        <xs:sequence>

          <xs:element ref="isbn"/>

          <xs:element ref="title"/>

          <xs:element ref="author" minOccurs="0" maxOccurs="unbounded"/>

          <xs:element ref="character" minOccurs="0" maxOccurs="unbounded"/>

        </xs:sequence>

        <xs:attribute ref="available"/>

      </xs:extension>

    </xs:complexContent>

  </xs:complexType>

  <xs:complexType name="personType">

    <xs:complexContent>

      <xs:extension base="elementWithID">

        <xs:sequence>

          <xs:element ref="name"/>

          <xs:element ref="born"/>

          <xs:element ref="dead" minOccurs="0"/>

          <xs:element ref="qualification"  minOccurs="0"/>

        </xs:sequence>

      </xs:extension>

    </xs:complexContent>

  </xs:complexType>

  <xs:element name="title">

    <xs:complexType>

      <xs:simpleContent>

        <xs:extension base="string255">

          <xs:attribute ref="lang"/>

        </xs:extension>

      </xs:simpleContent>

    </xs:complexType>

  </xs:element>

  <xs:element name="library">

    <xs:complexType>

      <xs:sequence>

        <xs:element ref="book" maxOccurs="unbounded"/>

      </xs:sequence>

    </xs:complexType>

  </xs:element>

  <xs:element name="book">

    <xs:complexType>

      <xs:complexContent>

        <xs:restriction base="bookTmp">

          <xs:sequence>

            <xs:element ref="isbn"/>

            <xs:element ref="title"/>

            <xs:element ref="author" minOccurs="0" maxOccurs="unbounded"/>

            <xs:element ref="character" minOccurs="0" maxOccurs="unbounded"/>

          </xs:sequence>

          <xs:attribute name="id" type="bookID"/>

          <xs:attribute ref="available"/>

        </xs:restriction>

      </xs:complexContent>

    </xs:complexType>

  </xs:element>

  <xs:element name="author">

    <xs:complexType>

      <xs:complexContent>

        <xs:restriction base="personType">

          <xs:sequence>

            <xs:element ref="name"/>

            <xs:element ref="born"/>

            <xs:element ref="dead" minOccurs="0"/>

          </xs:sequence>

          <xs:attribute ref="id"/>

        </xs:restriction>

      </xs:complexContent>

    </xs:complexType>

  </xs:element>

  <xs:element name="character">

    <xs:complexType>

      <xs:complexContent>

        <xs:restriction base="personType">

          <xs:sequence>

            <xs:element ref="name"/>

            <xs:element ref="born"/>

            <xs:element ref="qualification"/>

          </xs:sequence>

          <xs:attribute ref="id"/>

        </xs:restriction>

      </xs:complexContent>

    </xs:complexType>

  </xs:element>

</xs:schema>