As Aaron said, DIM is used to declare arrays, which can have up to 4 "dimensions". In multi-dimensional arrays, each primary element is itself its own array with its own elements. Such that... DIM AR[2,2] ...will declare a 2-dimensional array, where you must first call the sub-array and then the element of the sub-array. In other words, AR[0] and AR[1] will each be a 2 element array.