Seniority in each grade of the service shall be determined by the year of substantive appointment to a post in the particular grade :
Provided.-
(i) that if two or more persons are appointed to posts in the same grade in the same year, a person appointed by promotion shall be senior to a person appointed by direct recruitment;
(ii) that the seniority inter-se of persons appointed to particular grade by direct recruitment on the basis of one and the same selection, except those who do not join service when a vacancy is offered to them, shall follow the order in which they have been placed in the list prepared by the Commission under rule 21;
(iii) that the seniority inter-se of persons appointed to posts in a particular grade by promotion shall follow the orders in which they have been placed in the list prepared under sub-rule [(4)] of rule 25; and
(iv) that the seniority or persons appointed by transfer from Government service, after the commencement of these rules, shall be determined ad hoc on the basis of their continuous length of substantive service on the analogous post;
(v) The seniority inter-se of the persons selected from different categories on the basis of seniority-cum-merit or merit, as the case may be, shall be determined on the basis of their continuous length of service on the equivalent posts.
(vi) The seniority inter-se of persons selected as a result of one and the same selection and appointed on the basis of merit alone shall be in the same order in which their names appear in the select list, irrespective of the period of continuous officiation.
(vii) that if a candidate belongs to the Scheduled Caste/Scheduled Tribes is promoted to immediate higher post/grade against a reserved vacancy earlier then his senior general/O.B.C. candidate who is promoted later to the said immediate higher post/grade, the general/O.B.C. candidate will regain his seniority over such earlier promoted candidate of the Scheduled Caste/Scheduled Tribes in the immediate higher post/grade.