Attribute 'src' cannot have a value...

[David Nedrow <dnedrow@mac.com>]

Given the template code below, I get a warning about the <imageobject  
role="fo"/> section. The error is...

     [warning] Attribute 'src' cannot have a value of "diagrams/ 
orgchart.pdf": should be either 'inherit' or a URI: src="url(...)".

I'm not sure if this indicates a problem with my markup, or if it's  
something specific to the fo processor I'm using (XEP).

The PDF output looks fine, so it's not making a functional  
difference, but I really dislike warnings. ;)

-David

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.4//EN"
                       "http://www.docbook.org/xml/4.4/docbookx.dtd"; [
<!ENTITY copyholder "John Q. Public">
]>
<?xml-stylesheet href="css/docbook.css" type="text/css"?>
<book>
<bookinfo>
   <mediaobject>
    <imageobject>
     <imagedata fileref="franklin-trans.png"/>
    </imageobject>
   </mediaobject>
   <title>Title</title>
   <subtitle>Sub-Title</subtitle>
   <authorgroup>
    <author>
     <firstname>John</firstname>
     <surname>Public</surname>
     <affiliation>
      <orgname>Foo University</orgname>
      <orgdiv>Geoblah Master's Program</orgdiv>
     </affiliation>
    </author>
   </authorgroup>
   <copyright>
    <year>2006</year>
    <holder>&copyholder;</holder>
   </copyright>
   <legalnotice>
    <para> This document expires one year from the last revision  
date.</para>
   </legalnotice>
   <revhistory>
    <revision>
     <revnumber>$Revision$</revnumber>
     <date>$Date$</date>
     <revremark> This document expires one year from the above  
revision date.
     </revremark>
    </revision>
   </revhistory>
</bookinfo>
<chapter>
   <title>Foo</title>
   <section>
    <title>Bar</title>
    <para>This is a test of the ligatures fi and fl.</para>
    <figure>
     <title>Mill flow diagram</title>
     <mediaobject>
      <imageobject role="html">
       <imagedata fileref="diagrams/orgchart.png"/>
      </imageobject>
      <imageobject role="fo">
       <!-- For autofit to work right, need XSL stylesheets =>1.69 -->
       <imagedata scalefit="1" width="100%" contentdepth="100%"  
format="PDF"
        fileref="diagrams/orgchart.pdf"/>
      </imageobject>
     </mediaobject>
    </figure>
    <figure id="query1">
     <title>Given SELECT statement</title>
     <programlisting><![CDATA[
printf("0123");
     ]]>
    </programlisting>
    </figure>
   </section>
</chapter>
<chapter>
   <title>Test Cases</title>
   <section>
    <title>Unit Case</title>
    <section>
     <title>Entrance Criteria</title>
     <para/>
    </section>
    <section>
     <title>Exit Criteria</title>
     <para/>
    </section>
    <section>
     <title>Test Procedure</title>
     <procedure>
      <step>
       <para/>
      </step>
     </procedure>
    </section>
    <section>
     <title>Actual Results</title>
     <para/>
    </section>
   </section>
</chapter>
<colophon>
   <para>This document was marked up using DocBook XML and  
transformed for print
    using the XEP FO engine from RenderX and the DocBook XSLT  
stylesheets by
    Norman Walsh.</para>
   <para>For the print version, the text font is Times; the heading  
font is
    Helvetica; and the code font is Linotype OCR A.</para>
</colophon>
</book>