All persons holding positions not included among those exempted by Charter Section 11.02 shall have a permanent status if:
(a) They were employed in such positions on November 18, 1957, the date on which the City Charter became effective;
(b) They had served satisfactorily in the positions they now hold for a period of six months before the effective date of this section (Ordinance 48-59, passed May 4, 1959); or
(c) They shall serve a probationary period of six months or such longer period as may be prescribed under the provisions of this chapter.