bug in fo stylesheets: no uri-specification in fo:external-graphic?

[Stefan Seefeld <seefeld@sympatico.ca>]

I'v been trying out xmlroff and its new ability to deal
with external graphics. To do this I generated a fo file
from a docbook article using the xsl-fo stylesheets.

The generated fo file contains elements such as

<fo:external-graphic src="images/ast.svg" ...>,

which xmlroff complains about because (apparently)
the content of the 'src' attribute isn't a uri-specification.
Who is right ?

Thanks,
		Stefan