When the data is not in the correct sequence for a sequenced array, the %LOOKUPxx built-in functions and the LOOKUP operation code may find different values. The %LOOKUPxx built-in functions may not find a data value even if it is present in the array.
Since a binary search is used by the %LOOKUPxx built-in functions for a sequenced array, and the correct function of a binary search depends on the data being in order, the search may only look at a few elements of the array. When the array is out of order, the result of a binary search is unpredictable.