  Recent articles have suggested that the quasi-two dimensional antiferromagnet
MnPS$_3$ may have non-reciprocal magnons, whereby magnons in a Brillouin zone
corner at +q have different energies than those at $-$q. The magnons along the
Brillouin zone boundaries were measured using neutron three-axis spectrometry,
paying careful attention to the resolution function, to determine whether such
non-reciprocity was present. The data show that, within the resolution, there
are no significant differences between the magnons in opposite Brillouin zone
corners.
