I'm reading papers about the phenomenon transition/transversion but there is something that I don't understand. How are these two phenomena represented in literature? For instance, one paper has "C:G -> T:A" and I can't figure if it is a transition (C->G and T->A) or a transversion (Cs and Gs to Ts and As). Another example: one paper refers as " G:C to A:T transitions". Isn't this a transversion?