Reflection operation dihedral

Tm then follows from the character table for Oh and eq. (4.4.20). (The easiest way of determining (r, ) is to look at the figure representing the set of points to be permuted (in this case, a cube) and determine the number of points that are unshifted under one operation from each class. This number is the character for that class in the permutation representation Tm. For example, each of the dihedral planes contains four points which are invariant under reflections in that plane.)... 

Use italic type for the letters in symmetry operations and structural point groups. The symbols (Schoenflies) are as follows E, identity C, cyclic D, dihedral T, tetrahedral O, octahedral I, icosahedral S, rotation-reflection and a, mirror plane. Align subscripts and superscripts. 

A rotation around an axis by x(360%) x sequential C operations A vertical mirror plane containing the principal rotation axis (the one of highest order) A horizontal mirror plane, one perpendicular to the principal rotation axis A dihedral mirror plane, one which bisects two cTy or operations An improper rotation axis rotation around an axis by 360% followed by reflection in a plane perpendicular to this axis X sequential S operations... 

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