I am reading an article and in one of the sections the article mentions the symmetry group.
The symmetry group of one of the objects the article talks about is the dihedral group of order 12, using this as an example the article talks about symmetry types denoted as : I,G,DD,R2,SD,D.
What is the meaning of the notation ? It's easy to see from the article that I is the id, but that's all I managed to figure out.
Edit: : link to the article - page 7 in the pdf, table 1 it is also said that "we define a symmetry type to be conjugacy class of subgroups of G"