Entitlements Upon Return to Work (a) An employee who returns to work after the expiration of maternity, parental, or pre-adoption leaves shall retain the seniority the employee had accumulated prior to commencing the leave and shall be credited with seniority for the period of time covered by the leave. (b) On return from maternity, parental, or pre-adoption leaves, an employee shall be placed in the employee's former position or in a position of equal rank and basic pay. (c) Notwithstanding Clauses 18.1(b) and 18.6, vacation entitlements and vacation pay shall continue to accrue while an employee is on leave pursuant to Clause 21.1 providing: (1) the employee returns to work for a period of not less than six months, and (2) the employee has not received parental allowance pursuant to 21.6; and (3) the employee was employed prior to March 28, 2001. Notwithstanding Clause 18.6(a) vacation earned pursuant to this clause may be carried over to the following year, or be paid out, at the employee's option. (d) Employees who are unable to complete the return to work period in (c) as a result of proceeding on maternity, parental or pre-adoption leave shall be credited with their earned vacation entitlements and vacation pay providing the employee returns to work for a period of not less than six months following the expiration of the subsequent maternity, parental or pre-adoption leave.