1. This Chapter does not apply to:

(a) individual contracts for self-employed persons;

(b) single-member schemes for self-employed persons;

(c) insurance contracts to which the employer is not a party, in the case of workers;

(d) optional provisions of occupational social security schemes offered to participants individually to guarantee them:

(i) either additional benefits,

(ii) or a choice of date on which the normal benefits for self-employed persons will start, or a choice between several benefits;

(e) occupational social security schemes in so far as benefits are financed by contributions paid by workers on a voluntary basis.

2. This Chapter does not preclude an employer granting to persons who have already reached the retirement age for the purposes of granting a pension by virtue of an occupational social security scheme, but who have not yet reached the retirement age for the purposes of granting a statutory retirement pension, a pension supplement, the aim of which is to make equal or more nearly equal the overall amount of benefit paid to these persons in relation to the amount paid to persons of the other sex in the same situation who have already reached the statutory retirement age, until the persons benefiting from the supplement reach the statutory retirement age.