Seeing as I was looking for additional data on this subject because I
am meant to be writting an essay for it (instead of surfing the
internet) I thought I'd tell you what I've found, briefly.  Anatta is,
as you say, part of the three marks of existence (the other 2 being
dukkha and anicca).  The essence of thisconcept is that there is no
eternal Self or soul which carries on after death and instead we are
merely a collection of groups of grasping (or khandha) which are in a
continual state of flux.  Rebirth is possible only because we are
driven by our desires and volitions.  This is envisioned as an
eternally turning wheel being drawn on by the bull of our cravings
(don't ask me!).  Anyway that's all that I've been able to unearth so
far, but If you find anything else please put it up soon so that other
people can use what is becoming an increasingly incvaluable source of
info.  Yours sincerely Matthew Adams