  The magnetic structure of RuO2 and the Ru atomic configuration are unknown. A
magnetic structure is inferred by confronting measured and calculated Bragg
diffraction patterns and adjusting the latter to achieve satisfactory
agreement. An accepted pattern, a magnetic symmetry, includes symmetry of sites
occupied by the magnetic ions. As a realistic starting point, we provide
diffraction patterns for a magnetic symmetry of RuO2, a descendent of the
tetragonal parent structure, which accommodates a departure of Ru axial dipoles
from the crystal c axis. A chiral signal and piezomagnetic effect are
permitted, and a linear magnetoelectric effect forbidden. Features of the
neutron diffraction pattern test the non-relativistic requirement of
altermagnetism, and we scrutinize published room-temperature data.
Specifically, one Bragg point is consistent with Ru orbital angular momentum
and magnetic quadrupole both zero, and the latter result is not expected from
non-relativistic altermagnetism. Azimuthal angle scans in resonant x-ray
diffraction are sensitive to the Ru site symmetry and the atomic configuration.
Acid tests of the studied magnetic symmetry include a chiral signature and null
intensity for unrotated photon polarization.
