In the former case, an employee, on fulfilling the prescribed conditions, can claim voluntary retirement as a matter of right, whereas in the latter case he cannot, because, despite the fact that he fulfils the prescribed eligibilities to apply for voluntary retirement, the discretion to accept such offer of retirement is vested in the employer, and the employer may or may not accept such an offer of the employee having regard to the needs and exigencies of service and other relevant considerations. In addition to the aforementioned two kinds of rules that may exist in a public service organization providing for voluntary retirement, a particular service organization may also evolve and introduce a special scheme in its discretion de hors the rules providing for voluntary retirement. If an employee seeks voluntary retirement under such Special Scheme, he can seek voluntary retirement strictly in terms of such Special Scheme and not de hors the Special Scheme, because, as already pointed out supra, no employee, after joining a public service, can claim voluntary retirement as a matter of right or course unless the rules governing terms and conditions of his service provide for such retirement. ”