alias LOCAL = 0;
alias SHARED = 1;
alias GLOBAL = 2;
alias CONSTANT = 3;

external (GLOBAL) globalDataFromElsewhere : Array[Vec[Float32,4]];

var (GLOBAL) globalData = Array[Vec[Float32, 4]]();

operateOnGlobalData(ptr: Pointer[Vec[Float32,4], GLOBAL]) { ... }