  The symmetry of long-range magnetic order in manganese telluride (alpha-MnTe)
is unknown. Likewise, its standing as an altermagnet. To improve the situation,
we present symmetry informed Bragg diffraction patterns based on a primary
magnetic order parameter for antiferromagnetic alignment between Mn dipoles. It
does not break translation symmetry in a centrosymmetric structure, in keeping
with an accepted definition of altermagnetism. Our templates serve x-ray
diffraction that benefits from signal enhancement using a Mn atomic resonance,
and neutron scattering. Even rank multipoles in magnetic neutron diffraction
reflect a core requirement of altermagnetism, because they are zero for strong
spin-orbit coupling. Symmetry in the templates demands that nuclear and
magnetic contributions possess the same phase, which enables standard neutron
polarization analysis on Bragg spots with overlapping contributions. However,
three of the four templates generate Bragg spots that do not appear in the
lattice (nuclear) diffraction pattern, i.e., Bragg spots that are
basis-forbidden and purely magnetic in origin. On the other hand, identical
symmetry demands a 90 deg phase shift between magnetic (time-odd) and
charge-like (time-even, Templeton-Templeton) contributions to x-ray scattering
amplitudes. Consequently, circular polarization in the primary beam of x-rays
is rotated. The difference in the intensities of a Bragg spot measured with
right- and left-handed circular primary polarization defines a chiral
signature. Further tests include predictions in three out four templates of
zero intensity in a specified channel of x-ray polarization. Diffraction
properties of a template are radically different from those of a parity-time
(PT)-symmetric antiferromagnet, for its symmetry allows a linear ME effect and
prohibits both a PM effect and a chiral signature.
