For the purposes of layoff, retrenchment, and closure, the total number of employees falling within the ambit of the definition clause of 'workman' under section 2(s) of the IDA, 1947, who are on the rolls of the industrial establishment shall be computed on an average basis during the preceding 12-month period. It implies that although falling under the definition of a workman, temporary, casual, or contract labor shall not be included in the calculation.