In menu Fritzing 0.9.3...
File -> Export -> for Production -> Etchable (SVG)...
You get following .svg files:
xxx_etch_copper_bottom.svg
xxx_etch_copper_bottom_mirror.svg
xxx_etch_copper_top.svg
xxx_etch_copper_top_mirror.svg
xxx_etch_mask_bottom.svg
xxx_etch_mask_bottom_mirror.svg
xxx_etch_mask_top.svg
xxx_etch_mask_top_mirror.svg
xxx_etch_paste_mask_bottom.svg
xxx_etch_paste_mask_bottom_mirror.svg
xxx_etch_paste_mask_top.svg
xxx_etch_paste_mask_top_mirror.svg
xxx_etch_silk_bottom.svg
xxx_etch_silk_bottom_mirror.svg
xxx_etch_silk_top.svg
xxx_etch_silk_top_mirror.svg
If you import and edit any of these files in Inkscape, after ungroup them you will notice that the tools Union, Difference, Intersection, Exclusion and Division (in the Path tab of Inkscape) do not act on these vectors as would act if we were editing a .svg graphic generated in Inkscape itself.