title: How to instantiate an XSD Element of an abstract type
body: <p>I'm a java programmer new to XML and web services. I'm trying to create an xml document that conforms to an XSD (which I didn't write) that contains the below snippet. What I want to do is call this web service to copy a mailing. There's an element called copy, which is of the abstract type "tns:CopyRequest". Since the element's type is abstract, Eclipse tells me I can't create one. There's a CopyMailingRequest type (which sounds like it's what I want), but I'm not sure how to instantiate it, since there's no element that extends that type. What am I missing?</p>
  
  <pre><code>&lt;xs:element name="copy" nillable="true" type="tns:CopyRequest"/&gt;
  
  &lt;xs:complexType name="CopyMailingRequest"&gt;
    &lt;xs:complexContent&gt;
      &lt;xs:extension base="tns:CopyRequest"&gt;
        &lt;xs:sequence&gt;
          &lt;xs:element name="fromId" type="tns:MailingId"/&gt;
        &lt;/xs:sequence&gt;
      &lt;/xs:extension&gt;
    &lt;/xs:complexContent&gt;
  &lt;/xs:complexType&gt;
  
  &lt;xs:complexType name="StandardMailingId"&gt;
    &lt;xs:complexContent&gt;
      &lt;xs:extension base="tns:MailingId"/&gt;
    &lt;/xs:complexContent&gt;
  &lt;/xs:complexType&gt;
  
  &lt;xs:complexType name="MailingId"&gt;
    &lt;xs:complexContent&gt;
      &lt;xs:extension base="tns:ObjectId"/&gt;
    &lt;/xs:complexContent&gt;
  &lt;/xs:complexType&gt;
  
  &lt;xs:complexType name="CopyRequest" abstract="true"&gt;
    &lt;xs:sequence&gt;
      &lt;xs:element name="newName" type="xs:string"/&gt;
    &lt;/xs:sequence&gt;
  &lt;/xs:complexType&gt;
  </code></pre>