Controlling transparency - php mapscript

[Alan Hale]

Hi

I've just learned how to set the transparency for a layer

    - $myLayer->set("transparency", 20);

But what I really want to do is set a semi-transparent fill for square 
polygons that I'm drawing on the fly from a MySQL database, but keep the 
outline of the squares opaque. Is this possible - and how?

Many thanks

Alan Hale
Aberystwyth
Wales