Hmm, Layer style sheet... It lets me thinking of print style. Define
the object color/line width/transparency for printing, I think like
autoCAD plot settings.
It is really useful for circuit diagram, or assembly illustration, etc.
One of the problems with inkscape is that to ensure the styles of each
element it specifies every style property in every object. this would
have to be changed to have styles work their way up from layers or
even the svg as a whole.
Best Regards, Martin Owens