Length Facets: length, minLength, maxLength

• The number of units allowed in a value

• For strings (string, normalizedString, token, QName, NCname, ID, IDREF, language, anyURI, ENTITY, NOTATION, and NMTOKEN) the units are characters

• For lists (IDREFS, ENTITIES, and NMTOKENS) the units are tokens

• For binary types (hexBinary, base64Binary) the units are bytes after decoding

• Must be a non-negative integer

• For example, to say that all names and titles must contain between 1 and 255 characters:

  <?xml version="1.0"?>
  <xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema">
  
    <xsd:element name="SONG" type="SongType"/>
   
    <xsd:simpleType name="Str255">
      <xsd:restriction base="xsd:string">
         <xsd:minLength value="1"/>
         <xsd:maxLength value="255"/>
      </xsd:restriction>
    </xsd:simpleType>
   
    <xsd:complexType name="SongType">
      <xsd:sequence>
        <xsd:element name="TITLE"     type="Str255"/>
        <xsd:element name="COMPOSER"  type="Str255"
          maxOccurs="unbounded"/>
        <xsd:element name="PRODUCER"  type="Str255" 
          minOccurs="0" maxOccurs="unbounded"/>
        <xsd:element name="PUBLISHER" type="Str255" 
          minOccurs="0"/>
        <xsd:element name="LENGTH"    type="xsd:duration"/>
        <xsd:element name="YEAR"      type="xsd:gYear"/>
        <xsd:element name="ARTIST"    type="Str255" 
          maxOccurs="unbounded"/>
      </xsd:sequence>
    </xsd:complexType>
   
  </xsd:schema>