ulink & target="_blank"

I've been searching through the docbook-apps archives, but unable to 
find a clear answer to this :

How can I set some, but not all ulinks to open in a new window :

The name  <ulink url="http://www.google.com"> Google  </ulink> should 
open in a new window.

The name  <ulink url="http://www.ford.com"> Ford  </ulink> should open 
in the current window.


Cheers,

Tristan
------------------------------
Tristan J. Fiedler
Postdoctoral Fellow - Stein Lab
Cold Spring Harbor Laboratory