  The derivation of absolute (moduli-independent) U-invariants for all N>2
extended supergravities at D=4 in terms of (moduli-dependent) central and
matter charges is reported. These invariants give a general definition of the
``topological'' Bekenstein-Hawking entropy formula for extremal black-holes and
reduce to the square of the black-hole ADM mass for ``fixed scalars'' which
extremize the black-hole ``potential'' energy.
