Odd Mime types?

I just added a couple of MIME types, image/vnd.dxf and drawing/x-dwf,
to my Jigsaw server.

The image/vnd.dxf type works fine, but the drawing/x-dwf type doesn't.

I've never heard of a "drawing" MIME type before and it doesn't appear
to be a real part of the standard.

Could this be the reason the drawing/x-dwf type isn't working
properly, or should I look somewhere else?

Thanks,

Terry Wilcox
terry@arcane.com