==================================
 Schema for ExpML 
==================================

<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
<!--Definition of Simple Elements-->
<!---->
  <xs:element name="number" type="xs:integer"/>
  <xs:element name="operator">
    <xs:simpleType>
      <xs:restriction base="xs:string">
        <xs:pattern value=" add | mult | div | sub "/>
      </xs:restriction>
    </xs:simpleType>
  </xs:element>
<!--Definition of Attributes-->
<!---->
<!--Definition of Complex Elements-->
<!---->
  <xs:element name="expression">
    <xs:complexType>
      <xs:choice>
        <xs:sequence>
          <xs:element ref="operator" minOccurs="0"/>
          <xs:element ref="expression" minOccurs="2" maxOccurs="2"/>
        </xs:sequence>
        <xs:element ref="number" minOccurs="1"/>
      </xs:choice>
    </xs:complexType>
  </xs:element>
<!---->
</xs:schema>