Creating HTML Links that Open in a New Window

How does one create links than open in a new window for html output of

<a href="document.html" target="_blank">external link</a>
or
<a href="document.html" rel="external">external link</a>

in DocBook 5?

<article ... xmlns:ns1="http://www.w3.org/1999/xlink">
...
...
<link ns1:type="simple" ns1:show="new" ns1:href="document.html">external
link</link>
...
...
</article>

does not produce the desired result (no new window)

Using most current releases of docbook-xml (rng) and docbook-xsl

Raymond