  It should be of interest, whether Dirac's equation involves all 16 basis
elements of his Clifford algebra $Cl_D.$ These include the 6 `tensorial'
$\sigma^{\mu\nu}$ with which the `Pauli terms' are formed. We find that these
violate a basic axiom of any *-algebra, when Dirac's $\Psi$ is canonical. Then
the Dirac operator is spanned only by the 10 elements
$1,i\gamma_5,\gamma^\mu,\gamma^\mu\gamma_5$ (which don't form a basis of $Cl_D$
because the $\sigma^{\mu\nu}$ are excluded).
