This is the best I can come up with. from the BMW X1 site but is applicable.
"To optimize the flow of power and the general standard of motoring refinement, the engine also comes with fully variable VALVETRONIC valve management, variable double-Vanos camshaft adjustment and an adjustment intake system (DISA)."
So, how the Germans turned "adjustable intake system" into the DISA acronym is beyond me in spite of being born there. Perhaps some things just don't translate well.