Return link to the symbol table
A fractional value next to the symbol indicates the height of the inversion centre above the XY plane. The mirror plane is separated from the centre of inversion by 1/4 of the repeat distance in the lattice along the axis direction. Although not shown, a fourfold inversion axis (-4) is also present with its inversion point at the same height as the mirror plane, i.e. at 1/4 along the axis from the centre of inversion.