[XeTeX] XeTeX, XeTeXpicfile, and transparency

[Philip TAYLOR]

Universe of discourse : Plain XeTeX.

I know that XeTeX has some support for transparency,
but the TeX Live documentation for XeTeXpicfile has
nothing to say on the subject :

> \XeTeXpdffile ‹filename› [ page ‹int› ] [ crop | media | bleed | trim | art ]
> [ scaled ‹int› | xscaled ‹int› | yscaled ‹int› | width ‹dimen› |
> height ‹dimen› | rotated ‹decimal› ]
> Insert (pages of) a . See below for explanation of optional arguments

If I were to want to insert an image with (say) 90% transparency
(i.e., 10% opacity), how might I best go about this ?

Philip Taylor