<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema">

<xsd:include schemaLocation="http://www.XMLSchemaReference.com/example/theme/catalog.xsd"/>
<xsd:include schemaLocation="http://www.XMLSchemaReference.com/example/theme/address.xsd"/>

<xsd:complexType name="compressedOrderType">
    <xsd:sequence>
        <xsd:element name="order"
                     minOccurs="1"
                     maxOccurs="unbounded">
            <xsd:complexType>
                <xsd:sequence>
                    <xsd:element name="customerID"
                                 type="xsd:token"/>
                    <xsd:element name="item"
                                 minOccurs="1"
                                 maxOccurs="unbounded">
                        <xsd:complexType>
                            <xsd:sequence minOccurs="1"
                                          maxOccurs="unbounded">
                                <xsd:element name="partNumber"
                                             type="partNumberType"/>
                                <xsd:element name="quantity"
                                             type="xsd:positiveInteger"/>
                            </xsd:sequence>
                        </xsd:complexType>
                    </xsd:element>
                </xsd:sequence>
                <xsd:attribute name="totalQuantity"
                               type="xsd:positiveInteger"
                               use="required"/>
                <xsd:attribute name="orderID"
                               type="xsd:token"
                               use="required"/>
                <xsd:attribute name="shipmentID"
                               type="xsd:token"
                               use="optional"/>
            </xsd:complexType>

            <xsd:key name="orderPartNumberKey">
                <xsd:annotation>
                    <xsd:documentation xml:lang="en">
                        The part number must be unique
                        within the order, but NOT
                        across orders.
                    </xsd:documentation>
                </xsd:annotation>
                <xsd:selector xpath="item"/>
                <xsd:field xpath="partNumber"/>
            </xsd:key>

        </xsd:element>
    </xsd:sequence>
</xsd:complexType>

<xsd:complexType name="shippedOrderSummaryType">
    <xsd:sequence>
        <xsd:element name="shipped"
                     minOccurs="1"
                     maxOccurs="unbounded">
            <xsd:complexType>
                <xsd:attribute name="shipmentID"
                               type="xsd:token"/>
                <xsd:attribute name="custID"
                               type="xsd:token"/>
                <xsd:attribute name="qty"
                               type="xsd:positiveInteger"/>
            </xsd:complexType>
        </xsd:element>
    </xsd:sequence>
</xsd:complexType>

<xsd:element name="idConstraintDemo">
    <xsd:complexType>
        <xsd:sequence>

            <xsd:element name="compressedOrder"
                         type="compressedOrderType">

                <xsd:key name="orderKey"
                         id="orderKey.key">
                    <xsd:annotation>
                        <xsd:documentation xml:lang="en">
                            The customerID uniquely identifies
                            each customer.
                        </xsd:documentation>
                    </xsd:annotation>
                    <xsd:selector xpath="order"
                                  id="orderKey.key.selector"/>
                    <xsd:field xpath="@orderID"
                               id="orderKey.key.field"/>
                </xsd:key>

                <xsd:unique name="orderShippedUnique"
                            id="orderShippedUnique.unique">
                    <xsd:annotation>
                        <xsd:documentation xml:lang="en">
                            The customerID uniquely identifies
                            each customer.
                        </xsd:documentation>
                    </xsd:annotation>
                    <xsd:selector xpath="order"/>
                    <xsd:field xpath="@shipmentID"/>
                </xsd:unique>

            </xsd:element>

            <xsd:element name="shippedOrderSummary"
                         type="shippedOrderSummaryType"/>

            <xsd:element ref="customerList"/>
            <xsd:element name="catalog" type="catalogType"/>

        </xsd:sequence>

    </xsd:complexType>

    <xsd:key name="customerKey">
        <xsd:annotation>
            <xsd:documentation xml:lang="en">
                The customerID uniquely identifies
                each customer.
            </xsd:documentation>
        </xsd:annotation>
        <xsd:selector xpath="customerList/*"/>
        <xsd:field xpath="@customerID"/>
    </xsd:key>

    <xsd:keyref name="customerRef" refer="customerKey">
        <xsd:annotation>
            <xsd:documentation xml:lang="en">
                Each order must refer to a known customer.
            </xsd:documentation>
        </xsd:annotation>
        <xsd:selector xpath="compessedOrder/order"/>
        <xsd:field xpath="customerID"/>
    </xsd:keyref>

    <xsd:key name="partNumberKey"
             id="partNumberKey.key">
        <xsd:annotation>
            <xsd:documentation xml:lang="en">
                The part number uniquely identifies
                each orderable item.
            </xsd:documentation>
        </xsd:annotation>
        <xsd:selector xpath="catalog/*"/>
        <xsd:field xpath="partNumber"/>
    </xsd:key>

    <xsd:keyref name="partNumberRef"
                id="partNumberRef.keyref"
                refer="partNumberKey">
        <xsd:annotation>
            <xsd:documentation xml:lang="en">
                Each order must refer to a known part number.
            </xsd:documentation>
        </xsd:annotation>
        <xsd:selector xpath="compressedOrder/order/item"/>
        <xsd:field xpath="partNumber"/>
    </xsd:keyref>

    <xsd:key name="orderedItemsKey"
             id="orderedItemsKey.key">
        <xsd:annotation>
            <xsd:documentation xml:lang="en">
                Identify ordered customers and
                shipping quantities.  Note that
                while schema already enforces
                the following constraint, the
                'key' also assures that there *is*
                a customerID and a shippingQuantity
                identified for each order
            </xsd:documentation>
        </xsd:annotation>
        <xsd:selector xpath="compressedOrder/order"/>
        <xsd:field xpath="@totalQuantity"/>
        <xsd:field xpath="customerID"/>
    </xsd:key>

    <xsd:keyref name="shippedItemsRef"
                id="shippedItems.keyref"
                refer="orderedItemsKey">
        <xsd:annotation>
            <xsd:documentation xml:lang="en">
                Ensure a shipped customer/qty
                for each ordered customer/qty
            </xsd:documentation>
        </xsd:annotation>
        <xsd:selector xpath="shippedOrderSummary/shipped"/>
        <xsd:field xpath="@qty"/>
        <xsd:field xpath="@custID"/>
    </xsd:keyref>

</xsd:element>

</xsd:schema>