The following periods of absence from work referred to in section 12 are not taken to be periods of employment when calculating the length of an employee's period of continuous employment—
(a) a period of unpaid leave in excess of 52 weeks (other than the initial 52 weeks) unless—
(i) the period of absence is taken to be a period of employment in accordance with the relevant employment agreement; or
(ii) the employer and the employee agreed in writing before the leave was taken that the period is taken to be a period of employment; or
(iii) the unpaid leave is taken on account of illness or injury or is any other form of leave provided for under the relevant employment agreement;
(b) an absence following the ending of the employee's employment described in section 12(6)(a) or (b);
(c) an absence caused by an employer standing down the employee described in section 12(7), (8) or (9).