  We show that if $\nabla R$ is a Jordan Szabo algebraic covariant derivative
curvature tensor on a vector space of signature (p,q), where q is odd and p is
less than q or if q is congruent to 2 mod 4 and if p is less than q-1, then
$\nabla R=0$. This algebraic result yields an elementary proof of the
geometrical fact that any pointwise totally isotropic pseudo-Riemannian
manifold with such a signature (p,q) is locally symmetric.
