Subsystemsof RR Lyrae Variable Stars in Our Galaxy . ... Field stars displaying more rapid motion and clusters with redderh orizontal branches constitute the spheroidal subsystem of the accreted outer halo, which is approximately a factor of three larger in size than the first two subsystems. ... Both the clusters and field stars belong to at least three Galactic subsystems: the thick disk and genetically related inner proto-disk halo, and the outer accreted halo. ...