  We show that a matrix is a Hermitian positive semidefinite matrix whose
nonzero entries have modulus 1 if and only if it similar to a direct sum of all
$1's$ matrices and a 0 matrix via a unitary monomial similarity. In particular,
the only such nonsingular matrix is the identity matrix and the only such
irreducible matrix is similar to an all 1's matrix by means of a unitary
diagonal similarity. Our results extend earlier results of Jain and Snyder for
the case in which the nonzero entries (actually) equal 1. Our methods of proof,
which rely on the so called principal submatrix rank property, differ from the
approach used by Jain and Snyder.
