<link xlink:href="..."> in XHTML output (DocBook XSL 1.71.1)

Hi,

I'm using DB5 (DTD) and the DocBook XSL stylesheets 1.71.1.

My source contains:

<link xlink:href="http://www.saxonica.com/"
      xlink:type="simple" 
      xlink:actuate="onRequest">http://www.saxonica.com</link>

When I transform the document with ~/xhtml/docbook.xsl, this results in:

<a href="#">http://www.saxonica.com</a>

Do I need to make the stylesheet aware of the fact that I feed it a DB5
document (DOCTYPE declaration?) to make linking via xlink:href work or
might this be a bug? All other elements (from those I am actually using)
seem to work fine.

Best regards
Christian Roth