This equation can be written as 

This equation can be written as  = ,
which shows that, even though  does not commute with elements of RC, it does
so at the cost of interchanging rows and columns. As a consequence, any symmetry that can be obtained by composing  and elements of R  C in any order can be
written in the form  with  2 RC. (The same symmetry can also be written in
the form  with  2 RC where  and  are the same except for the interchange
of rows and columns.)