XSL FO: scaling graphics

Can someone advise me about scaling graphics in FO? Is the following right?

a) I want the graphic a fixed size:

  <fo:external-graphic src="foo" content-width="4in"/>

b) I want a fixed width and height, and non-uniform scale:

  <fo:external-graphic src="foo" scaling="non-uniform"
        content-width="4in" content-height="4in"/>

c) I want the graphic to occupy 80% of the width of the enclosing box:

  <fo:external-graphic src="foo"  content-width="90%"/>

d) I want the graphic scaled to 50% of its natural size

 ?????????????????


I don't see a combination of properties which lets me express d). Any suggestions?

Sebastian Rahtz



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