Section 17 in The Madurai City Municipal Corporation Service Rules, 1975
17. Duty on temporary promotion to count for probation in lower post. - A probationer in any class or category of the service who is promoted temporarily under the provisions of rule 8 of these rules to a higher class or category of the service shall be entitled to count towards his probation, if any in the former class or category, the period of duty performed by him in the latter class or category, as the case may be, during which he would have held the post in the former class or category, but for his temporary appointment on promotion.
