Interesting, here is the po.xsd (this is included in the invoiceschema.xsd 
which is used by po.xml, I put them in separate messages):

<?xml version="1.0" encoding="UTF-8"?>
<xsd:schema xmlns="http://www.skatestown.com/ns/po"
            xmlns:xsd="http://www.w3.org/2001/XMLSchema"
            targetNamespace="http://www.skatestown.com/ns/po">

   <xsd:annotation>
      <xsd:documentation xml:lang="en">
         Purchase order schema for SkatesTown.
      </xsd:documentation>
   </xsd:annotation>

   <xsd:element name="po" type="poType"/>

   <xsd:complexType name="poType">
      <xsd:sequence>
         <xsd:element name="billTo" type="addressType"/>
         <xsd:element name="shipTo" type="addressType"/>
         <xsd:element name="order">
            <xsd:complexType>
               <xsd:sequence>
                  <xsd:element name="item" type="itemType"
                               maxOccurs="unbounded"/>
               </xsd:sequence>
            </xsd:complexType>
         </xsd:element>
      </xsd:sequence>
      <xsd:attribute name="id" use="required"
                     type="xsd:positiveInteger"/>
      <xsd:attribute name="submitted" use="required"
                     type="xsd:date"/>
      <xsd:attribute name="customerId" use="required"
                     type="xsd:positiveInteger"/>
   </xsd:complexType>

   <xsd:complexType name="addressType">
      <xsd:sequence>
         <xsd:element name="name" type="xsd:string" minOccurs="0"/>
         <xsd:element name="company" type="xsd:string" minOccurs="0"/>
         <xsd:element name="street" type="xsd:string"
                      maxOccurs="unbounded"/>
         <xsd:element name="city" type="xsd:string"/>
         <xsd:element name="state" type="xsd:string" minOccurs="0"/>
         <xsd:element name="postalCode" type="xsd:string"
                      minOccurs="0"/>
         <xsd:element name="country" type="xsd:string" minOccurs="0"/>
      </xsd:sequence>
      <xsd:attribute name="id" type="xsd:ID"/>
      <xsd:attribute name="href" type="xsd:IDREF"/>
   </xsd:complexType>

   <xsd:complexType name="itemType">
      <xsd:sequence>
         <xsd:element name="description" type="xsd:string"
                      minOccurs="0"/>
      </xsd:sequence>
      <xsd:attribute name="sku" use="required">
         <xsd:simpleType>
            <xsd:restriction base="xsd:string">
               <xsd:pattern value="\d{3}-[A-Z]{2}"/>
            </xsd:restriction>
         </xsd:simpleType>
      </xsd:attribute>
      <xsd:attribute name="quantity" use="required"
                     type="xsd:positiveInteger"/>
   </xsd:complexType>

</xsd:schema>


"Martin Honnen" <mahotrash@y...> wrote in message 
news:4752b347$0$4371$9b4e6d93@n......
> geoff wrote:
>
>> Why does this not work:
>>
>>    <billTo id="addr-1">
>>       <company>The Skateboard Warehouse</company>
>>       <street>One Warehouse Park</street>
>>       <street>Building 17</street>
>>       <city>Boston</city>
>>       <state>MA</state>
>>       <postalCode>01775</postalCode>
>>    </billTo>
>>
>>    <shipTo href="addr-1"/>
>>
>> . . . billTo and shipTo are defined as the same in the schema and I 
>> included the following in the schema definition:
>>
>>      <xsd:attribute name="id" type="xsd:ID"/>
>>       <xsd:attribute name="href" type="xsd:IDREF"/>
>>
>> . . . however, xml notepad says, 'the element shipTo has incomplete 
>> contents'.  If I populate shipTo with the same info as billTo, it works 
>> fine but the referencing of billTo does not seem to work or is it a 
>> limitation of xml notepad?
>
> If the schema for shipTo defines child elements then you have to include 
> those child elements literally. There is no way to include them using a 
> link mechanism, that is not how XSD schemas work.
> All ID/IDREF allow you is to refer to other components for instance
>   <address id="addr1">
>       <company>The Skateboard Warehouse</company>
>       <street>One Warehouse Park</street>
>       <street>Building 17</street>
>       <city>Boston</city>
>       <state>MA</state>
>       <postalCode>01775</postalCode>
>   </address>
>
>   <billTo href="addr1"/>
>   <shipTo href="addr1"/>
> but then the schema would not define child elements for billTo and shipTo, 
> it would just define the attribute and its type.
>
>
> -- 
>
> Martin Honnen
> http://JavaScript.FAQTs.com/