Jump install (JI) is a system 'glitch' that was discovered in the Guilty Gear series. The execution is done in a way where during any grounded string, you input a "jump" while not actually jumping. (Slayer doing standing S-S string, and pressing "UP" inbetween) The implication is that the game actually "stores" the jump state so that later in the combo where you would normally NOT be able to jump, you can. 

Last updated on February 8, 2010 by haunts