“…We show that q(H ) is real in classes A, AI, AII, BDI, and D, it is complex in classes AIII, CI, and DIII, and it cannot be defined in classes C and CII. When q is real, sgn q(H ) equals the parity of the topological invariant in d = 0 dimensions [3,9,21,26,27]. In the presence of an additional symmetry [H,U ] = 0,{C,U } = 0, where C is the chiral symmetry operator, q becomes real also in classes AIII, CI, and DIII [28].…”