Enumeration

• The enumeration facet lists all allowed values

• Applies to all simple types except boolean

• For example, to say that the publisher must be one of the oligopoly that controls 90% of U.S. music (Warner-Elektra-Atlantic, Universal Music Group, Sony Music Entertainment, Inc., Capitol Records, Inc., BMG Music)

  <?xml version="1.0"?>
  <xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema">
  
    <xsd:element name="SONG" type="SongType"/>
   
    <xsd:simpleType name="oligopolyMember">
      <xsd:restriction base="xsd:string">
        <xsd:enumeration value="Warner-Elektra-Atlantic"/>
        <xsd:enumeration value="Universal Music Group"/>
        <xsd:enumeration value="Sony Music Entertainment, Inc."/>
        <xsd:enumeration value="Capitol Records, Inc."/>
        <xsd:enumeration value="BMG Music"/>
      </xsd:restriction>
    </xsd:simpleType> 
   
    <xsd:complexType name="SongType">
      <xsd:sequence>
        <xsd:element name="TITLE"     type="xsd:string"/>
        <xsd:element name="COMPOSER"  type="xsd:string"
          maxOccurs="unbounded"/>
        <xsd:element name="PRODUCER"  type="xsd:string" 
          minOccurs="0" maxOccurs="unbounded"/>
        <xsd:element name="PUBLISHER" type="oligopolyMember" 
          minOccurs="0"/>
        <xsd:element name="LENGTH"    type="xsd:duration"/>
        <xsd:element name="YEAR"      type="xsd:gYear"/>
        <xsd:element name="ARTIST"    type="xsd:string" 
          maxOccurs="unbounded"/>
      </xsd:sequence>
    </xsd:complexType>
   
  </xsd:schema>