User blog comment:Crimson and Darkness/Volume 25 discussion blog/@comment-31654305-20180420030825/@comment-26952857-20180420043734

yes, that does mean isse will have 2 more form AxA and ExE,.but isse's form is still unnamed, we dont know the abbreviation for it yet, for both ExE and AxA. there are 3 diffrent ExE.

1- ExE: refer to a world that's official name is Evie Etoulde, contain some meca life forms called Ul+Chichigami.... more info in Ex volume.

2- ExE: refer to a future organizasion that gonna form int he future to fight ULs who gonna come from ExE world ( same as DxD is also name of organization that was formed to fight the Evil Dragons)

3- ExE: Isse future powerup name we dont actually knonw what it mean. that's why it was written " Issei’s E×E form doesn’t have a meaning yet"