OR
A percentage of MAC behind the wing LE
Brian W

Errrrr, not neccessarily so; The wing leading edge will be the zero
MAC point only if the leading edge of the wing is a straight line,
otherwise as in the LS-8, zero MAC will be located behind the leading
edge. I know a guy that made this incorrect assumption on the first
flight of an RS-15 and he flew the whole flight (rather short) with
the stick full back because his CG was forward of the forward limit.
He considered bailing out, but found he could keep the nose up if he
flew 80 knots. He landed OK touching down at 80.

I like to refer to the CG in a percentage of the allowable range. The
Genesis likes to be about 85% of the allowable range which is; 0 to
5.25" aft of root rib and 85% is 4.5"aft. After adjusting the CG, give
her a test drive. If you find you are trimming forward when entering a
thermal, your CG is too far aft.
Cheers,
JJ