User blog comment:B214/Question and Answers 6/@comment-29362784-20170329203907/@comment-30924344-20170329204552

ExE and AxA have no meanings. DxD has three meanings: Dragon of Dragons, Devils-Dragon-Downfall an any names starting with the letter "D" can also be forcefully added. It also has the meaning of the teams goal which is to protect Great Red who is known as [D×D]. The final meaning is Diabolos Dragon which refers to both Issei and Vali.