I tested all "Datum"-features today and the result is... strange.
See attached pdf in Mantis tracker issue #2758
To me its seams to be a lot of bugs involved in these "Datum"-features.
PS. Regarding point, lines and planes attachement/base, as it is now they are bound to a body, i.e. body is parent and point, lines and planes are children. It shall be the other way around. And for that matter they shall live in their own "container", see issue #2686