Uncoding the Code

Does anyone else out there ever get curious as to what the letters mean after a religious' name? I come across a whole variety of combinations of letters, particularly when reading books (after author's names). So, does anyone know the secret to uncoding the various religious order codes?

Off the top of my head I know OP, OMI, OSB, LC, SM, SJ and MC but I think that's about it. . . as for the others, it's always a guessing game. How about SDS, CS, and OFM? I have no clue.