(10) In this Part,

“mandatory posting date” means,

(a) the second anniversary of the effective date, in respect of employers in the public sector and in respect of employers in the private sector who have at least 500 employees on the effective date,

(b) the third anniversary of the effective date, in respect of employers in the private sector who have at least 100 but fewer than 500 employees on the effective date,

(c) the fourth anniversary of the effective date, in respect of employers in the private sector who have at least fifty but fewer than 100 employees on the effective date and who have posted a notice under section 20, and

(d) the fifth anniversary of the effective date, in respect of employers in the private sector who have at least ten but fewer than fifty employees on the effective date and who have posted a notice under section 20. R.S.O. 1990, c. P.7, s. 10.