<xsd:schema xmlns:xsd=“www.w3.org/2001/XMLSchema

      targetNamespace="http://foo"
      xmlns="http://foo"
      xmlns:a="http://foo">

<xsd:element name="foo">
        <xsd:complexType>
              <xsd:sequence>  
                      <xsd:element name="em" 
                              type="emType" 
                              maxOccurs="unbounded"
                              form="qualified"/>              
              </xsd:sequence>
        </xsd:complexType>    
</xsd:element>

<xsd:simpleType name="emp0001_3Type">
        <xsd:restriction base="xsd:ID">
                <xsd:enumeration value="EMP0040"/>              
                <xsd:enumeration value="EMP0003"/>
                <xsd:enumeration value="EMP0004"/>
                <xsd:enumeration value="EMP0005"/>
        </xsd:restriction>
</xsd:simpleType>

<xsd:simpleType name="emp0004_5Type">
        <xsd:restriction base="xsd:ID">
        <xsd:enumeration value="EMP0002"/>
                <xsd:enumeration value="EMP0090"/>
                <xsd:enumeration value="EMP0007"/>
        </xsd:restriction>
</xsd:simpleType>

<xsd:simpleType name="unboundedEmType">
              <xsd:union memberTypes="a:emp0001_3Type emp0004_5Type">
                      <xsd:simpleType>
                              <xsd:restriction base="xsd:ID">
                                      <xsd:enumeration value="EMP0099"/>                
                              </xsd:restriction>
                      </xsd:simpleType>               
              </xsd:union>
</xsd:simpleType>

<xsd:simpleType name="emType">
          <xsd:restriction base="unboundedEmType">
              <xsd:pattern value="EMP[0-9]*"/>
          </xsd:restriction>
</xsd:simpleType>

</xsd:schema>