Run-time arrays are not sequence checked. If you process a SORTA (sort an array) operation, the array is sorted into the sequence specified on the definition specification (the ASCEND or DESCEND keywords) defining the array. If the sequence is not specified, the array is sorted into ascending sequence. When the high (positions 71 and 72 of the calculation specifications) or low (positions 73 and 74 of the calculation specifications) indicators are used in the LOOKUP operation, the array sequence must be specified.