SVG Documentation error ?

Hello

   Making some tests with inline and extern SVG files, i think i found a
 little error. As far as i think Bob may be concerned, i'll post it here.

   Following the documentation (lean and mean documentation i think :-), i
 wanted to use an extern SVG file in a DocBook document which stated :

     <mediaobject id="CirclesPicture">
      <imageobject role="fop">
       <imagedata format="SVG"  fileref="svg-extern-circles.svg"/>
      </imageobject>
      <imageobject role="html">
       <imagedata format="PNG"  fileref="svg-extern-circles.png"/>
      </imageobject>
     </mediaobject>

  When transforming with xalan-j (2.5.2), docbookx.dtd (4.2) and docbook.xsl
  (1.64.1) to FO, it generates :

	<fo:external-graphic src="url(svg-extern-circles.png)" width="auto"
	height="auto" content-width="auto" content-height="auto"/>

  Which i thought was a automatic conversion with Batik (1.5, installed too)
  That was not really expected and i tried to change the docbook source to

	<imageobject role="fo">
	   <imagedata format="SVG"  fileref="svg-extern-circles.svg"/>
	</imageobject>

  The very same conversion produced the following code :

	<fo:external-graphic src="url(svg-extern-circles.svg)" width="auto"
	height="auto" content-width="auto" content-height="auto"/>

  So this time the extern SVG file was referenced.

  I am not sure this isn't a side effect of some mis-configuratio of mine,
  so i ask here about it. And if it is an error, well that won't degrade
  the quality of Bob's paper :)

  See you later
  Nicolas Pillot