Is there a way to save an Inkscape drawing so the layer information will not be removed? When I save the drawing as plain SVG and try to open it again in Inkscape, all layers are gone.
DXF-format preserves layer-information. Although many other information is lost throught this way (f.e. fillcolors), and paths might have to be reconnected.
So the answer to this question (preserving layer-information) would be, to save and open as
DXF, although it's not very satifying (other information is lost).
(Unfortunately I do not have enough Rep to comment on questions, otherwise I would have done that, instead of writing an answer)