The selective omission is a memory bias. In collective memory it's a bias where a group (state, media, public opinion) work to forget some traumatic memories. This expressions is often used for post-war rewriting of history in a more coherent way according to local stereotypes and moral values. That's denying war atrocities. The viewer often forget their own side's atrocities or suggest they were done by the opposite side, while the other side's atrocities are freely exposed. On the winning side, it's closely related to the concept of fair quest and clean war, which claim to kill only warriors in fights.