51F05 Absolute planes
51F10 Absolute spaces
51F15 Reflection groups, reflection geometries, See also {20H10,
20H15; for Coxeter groups, See 20F55}
51F20 Congruence and orthogonality, See also {20H05}
51F25 Orthogonal and unitary groups, See also {20H05}
51F99 None of the above but in this section