  This is a note showing that, contrary to our lasting belief, the
nonadditivity X(1+2)=X(1)+X(2)+\alpha X(1)X(2) is not a true physical property.
\alpha in this expression cannot be unique for a given system. It unavoidably
depends on how one mathematically divides the system and cannot be used to
characterize nonadditivity. As a matter of fact, its use is mathematically
inconsistent.
