With XLink (XHTML 2.0)

Database inclusions using XLink:

  <html>
    <a xlink:href="headstuff.xml" xlink:show="embed"
       xlink:actuate="onLoad"/>
    <body>
      <a xlink:href="adbanner.xml" xlink:show="embed"
         xlink:actuate="onLoad"/>
      <a xlink:href="dataquery.xml" xlink:show="embed"
         xlink:actuate="onLoad"/>
    </body>
  </html>