path direction

I like that SVG paths can be defined just once in the <defs> element and
then reused in rendering the paths, labeling the paths and defining
animation that traverses the paths.  I've just started to delve into
connecting SVG with a directed graph library and I'm beginning to think
that I'll need to duplicate the path definitions: one definition for
each direction.  There are cases when <textPath> requires the path in
one direction in order for the text to appear on the preferred side of
the path, but <mpath> requires the path in the other direction for
animating a shortest path solution.  Does SVG 1.1 have some path
direction control that I've overlooked?
 
Regards,
Greg