Choices

• xsd:choice requires exactly one of a group of specified elements to appear

• The choice can have minOccurs and maxOccurs attributes that adjust this from zero to any given number.

<xsd:complexType name="SongType">
  <xsd:sequence>
    <xsd:element name="TITLE" type="xsd:string"/>
    <xsd:element name="COMPOSER" type="PersonType"/>
    <xsd:choice minOccurs="0" maxOccurs="unbounded">
      <xsd:element name="PRODUCER" type="PersonType"/>
      <xsd:element name="COMPOSER" type="PersonType"/>
      <xsd:element name="ARTIST"   type="xsd:string"/>
    </xsd:choice>
    <xsd:element name="ARTIST" type="xsd:string"/>
    <xsd:element name="PUBLISHER" type="xsd:string"
                 minOccurs="0"/>
    <xsd:element name="LENGTH" type="xsd:string"/>
    <xsd:element name="YEAR"   type="xsd:string"/>
    <xsd:element name="PRICE" type="xsd:string" minOccurs="0"/>
  </xsd:sequence>
</xsd:complexType>