XML Schema notation Element

<notation
id=ID
name=NCName
public=anyURI
system=anyURI
any attributes
>

(annotation?)

</notation>

Optional. Specifies a URI corresponding to the system identifier

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

<xs:notation name="gif" public="image/gif" system="view.exe"/>
<xs:notation name="jpeg" public="image/jpeg" system="view.exe"/>

<xs:element name="image">
  <xs:complexType>
    <xs:simpleContent>
      <xs:attribute name="type">
        <xs:simpleType>
          <xs:restriction base="xs:NOTATION">
            <xs:enumeration value="gif"/>
            <xs:enumeration value="jpeg"/>
          <xs:restriction>
        </xs:simpleType>
      </xs:attribute>
    </xs:simpleContent>
  </xs:complexType>
</xs:element>

</xs:schema>

The "image" element in a document could look like this:

<image type="gif"></image>