Summarize the following court judgment. ition No. 8353 of 1981. Under Article 32 of the Constitution of India P.P. Rao and Parijat Sinha for the Petitioners. M.M. Abdul Khader	 Girish Chandra and Miss A. Subhashini for the Respondents. Medical Service in the Indian Railways is structured in ascending levels. At the base	 for the purpose of this case	 is the cadre of Assistant Divisional Medical Officers Class I (who before January 1	 1973 were described as Assistant Medical Officers Class II). Above them is the cadre of Divisional Medical Officers. The next above is the cadre of Medical Superintendents. Still higher rank Chief Medical Officers	 and the apex of the hierarchy is held by the Director General of Medical Services. There are eight petitioners. They were Assistant Medical Officers Class II and had been confirmed in that grade	 one petitioner in 19 62 and the others in 1963. During the years 1970 to 1972	 the petitioners were selected by Departmental Promotion Committees for officiating appointments to the Class I posts of Divisional Medical Officers	 when the Indian Railway Medical Service (District Medical Officers) Recruitment Rules	 1965 were in force. Those rules were repealed and replaced by the Indian Railways Medical Service (District Medical Officers) Recruitment Rules	 1973. Under the Rules of 1965 and the Rules of 1973	 the posts of District Medical Officers were treated as selection posts. To give effect to the recommendations of the Third Pay Commission	 the scales of pay of existing categories of officers were revised. The existing pay scale of Rs. 350 900 attached to the posts of Assistant Medical Officer was revised and split into two pay scales	 a higher Class I scale of Rs. 700 1600 and a lower Class II scale of Rs. 650 1200. The posts of Assistant Medical Officers were divided into those carrying the higher pay scale and those carrying the higher pay scale. A very large number of posts of Assistant Medical Officer were upgraded to the higher pay scale of Rs. 700 1600	 and were designated as "Assistant Divisional Medical Officer". The petitioners were placed in the higher pay scale of Rs. 700 1600 and were designated as Assistant Divisional Medical Officers with effect from 827 January 1. 1973. The screening of over 2000 Assistant Medical Officers for the purpose of upgrading them to the higher scale kept the Screening Committee busy from 1974 to 1976 or so	 and practically no recruitment was made during those year either by permanent promotion or direct recruitment to the posts of Divisional Medical Officer. The rules of 1973 were replaced by the Indian Railway Medical Service (Divisional Medical Officers/Senior Medical Officers) Recruitment Rules	 1975. These	 in their turn	 yielded place to the Indian Railway Medical Service (Chief Medical Officers	 Additional Chief Medical Officers	 Medical Superintendents and Divisional Senior Medical Officers Recruitment Rules	 1978. Under the Rules of 1978	 promotion is effected on the principle of "non selection"	 an expression in the Rules which is construed by the Railway administration as "seniority cum suitability". By a letter No. E (O) 1 78/SR 6/14 dated October 30	 1979 the Railway Board published a combined seniority list of Divisional Medical Officers recruited directly or by promotion. The respondents Nos. 4 to 64 were shown in that list. They include promotees as well as direct recruits. The petitioners did not find place in the seniority list. Subsequently	 on the basis of their position in that seniority list	 some of the respondent Divisional Medical Officers were appointed to officiate as Medical Superintendents by a Railway Board letter No. E(O)III 81 PN 6/199 dated August 31	 1981. The petitioners challenge the combined seniority list of Divisional Medical Officers and the officiating promotions to the posts of Medical Superintendents. The petitioners contend that the seniority assigned to the respondents Nos. 4 to 64 and the consequent promotions made thereafter violate Articles 14 and 16(1) of the Constitution. The grievance operates in two dimensions	 against the promotee respondents and against the direct recruit respondents. We propose to consider first the grievance of the petitioners in respect of the seniority accorded to the promotee respondents as Divisional Medical Officers and their promotion to officiate as Medical Superintendents. The case of the petitioners is that the petitioners were promoted as Divisional Medical Officers much before the promotee respondents	 that their promotion was made 828 by selection on the basis of merit adjudged by Departmental Promotion Committees under the Rules of 1965	 that they had continued in service as Divisional Medical Officers against vacancies in permanent posts without interruption for periods ranging respectively between 8 years to 12 years	 and yet the promotee respondents	 who had held such posts for shorter periods	 had been confirmed before the petitioners and shown senior in the seniority list and preferred for promotion as Medical Superintendents. It is contended that the petitioners should have been confirmed in the normal course	 the order of their promotion against permanent vacancies. The petitioners submit that the promotee respondents have been confirmed zone wise	 and such confirmation cannot serve as a proper reference for determining seniority	 because when confirmation is granted zone wise	 it depends on the fortuitous accrual of vacancies arise arbitrarily at different times and in different numbers in different individual zone. The petitioners contend that if the date of confirmation is adopted as the criterion	 confirmation should not be reckoned on a zonal basis	 but as if the vacancies arose in a single all India structure for	 the petitioners say	 a seniority list prepared for the purpose of Promotion to the post of Medical Superintendents	 which is an all India cadre	 should properly be drawn on an all India basis. The petitioners urge that if confirmation has to be considered zone wise	 then for the purpose of promotion to the all India cadre of Medical Superintendents the only logical and uniform criterion should be the total length of continuous service as Divisional Medical Officers reckoned from the date of promotion. It is a criterion which makes the arbitrary chance of confirmation against fortuitous vacancies in individual zones irrelevant. Finally	 the petitioners urge that for the purpose of fixing seniority in the grade of Divisional Medical Officers the seniority ruling in the grade of Assistant Medical Officers or Assistant Divisional Medical Officers is of no material significance because under the Rules in force when the Promotions in instant case were made promotions were governed by the principle of selection on the basis of merit. The respondents	 on the other hand	 maintain that the seniority list has been correctly prepared	 that it contains the names of only those officers who were either directly recruited as Divisional Medical Officers or had been approved for permanent promotion against the quota of posts reserved for them in vacancies allotted among the individual Railways on the basis of the cadre position of each Rail 829 way	 and that none of the petitioners qualified for inclusion in the seniority list as they had been promoted in an officiating capacity to temporary vacancies in the posts of Divisional Medical Officers. The respondents contend that the petitioners have no right to be treated at par with those officers who were holding permanent posts on a confirmed basis	 as confirmation was made on the basis of their selection for permanent promotion as Divisional Medical Officers. It is stated that seniority was also fixed on that basis. The respondents rely on a practice	 followed by the Railway Administration for several years	 under which three Select Lists were prepared. List A set out the names of officers selected for substantive promotion against permanent vacancies. List B included the names of officers selected for officiating promotion against temporary vacancies. These officers were also considered subsequently by Departmental Promotion Committees for permanent promotion along with other eligible officers in the field. The petitioners were placed in list B. The third list C	 bore the names of officers included in List by earlier Departmental Promotion Committees but not considered as "suitable yet" for substantive promotion by subsequent Departmental Promotion Committees. It is stated that in the Railway Administration	 Class II officers were considered for substantive appointment to permanent vacancies in Class I posts for officiating appointment against temporary vacancies in Class I posts. In each case	 there was a separate selection by a Departmental Promotion Committee	 and the selection was made zone wise. The Departmental Promotion Committees	 after considering the officers at five to six times the number of vacancies	 made a selection on an assessment of their Confidential Records. It is stated that officers selected for officiating appointment	 and subsequently coming within the field of consideration for permanent appointment against permanent vacancies	 were also considered for selection by subsequent Departmental Promotion Committees. In this manner	 it is said	 all eligible Class II officers were considered for permanent appointment against permanent vacancies	 and the most meritorious were selected. It is pointed out that this practice was terminated in the Medical Department of the Railways after 1972	 because with effect from January 1	 1973	 the Class II posts of Assistant Medical Officer were upgraded as Class I posts of Assistant Divisional Medical Officers. According to the respondents	 at no time during the period ending with the year 1972	 whenever Departmental Promotion Committees met for selecting officers against permanent vacancies 830 did any of the petitioners fall within the field of consideration for permanent appointment in view of their place of seniority in the class II posts. It is also submitted that the promotion of the petitioners	 then Assistant Medical Officers	 to the post of Divisional Medical Officers in an officiating capacity against temporary vacancies cannot be traced to the Rules of 1965 or the Rules of 1973 because those rules dealt with promotion to permanent vacancies only. Nor could the petitioners	 when they became Assistant Divisional Medical Officers with effect from January 1	 1973	 claim the benefit of the said Rules because those rules provided for selection of class II officers to class I posts. The respondents urge that the principle which truly governs the petitioners in the matter of promotion from the posts of Assistant Divisional Medical Officers is the principle of seniority cum suitability in the former grade embodied in the Rules of 1978. It is denied that this construction would amount to giving retrospective operation to the Rules of 1978. It is explained that when the question of preparing the seniority list arose	 the Rules of 1978 were in operation	 and they provided for permanent promotion on the basis of seniority cum suitability	 and the rule of selection on merit operating under the earlier Rules no longer prevailed	 and	 in any event	 could not apply when an Assistant Divisional Medical Officer	 which was a Class I post	 was considered for promotion to the Class I post of Divisional Medical Officer Apparently	 the promotee respondents were senior to the petitioners as Assistant Medical Officers or Assistant Divisional Medical Officers	 and that seniority was made the basis of permanent promotion to the grade of Divisional Medical Officers. The respondents dispute the proposition that promotion to the grade of Divisional Medical Officers must be made on the basis of the total length of service rendered as Assistant Medical Officers and Assistant Divisional Medical Officers considered on an all India basis as	 they assert	 promotion to vacancies has to be considered zone wise. A perusal of the Rules of 1965 shows that there were 101 posts in the grade of Divisional Medical Officers. The Rules of 1973 mention 109 posts. The posts are not divided between permanent posts and temporary posts	 and we must assume that the Rules refer to permanent posts only. It appears that proceedings were taken by the Railway Administration from time to time for the promotion of Assistant Medical Officers	 to the Class I posts of Divisional Medical Officers. The Railway Ministry indicated the number of existing vacancies for the purpose of permanent promotion and the number of 831 anticipated vacancies for the purpose of officiating appointment	 the number under each category being specified zone wise. The selection for both categories was made on the basis of merit. It may be noted that both under the Rules of 1965 and the Rules of 1973	 the posts of Divisional Medical Officers were regarded as selection posts. A Class I Departmental promotion Committee met on February 20	 1970 and considered the case of candidates who had completed five years and above of service as Assistant Medical Officers for such recruitment. Both for substantive promotion and for officiating promotion the field of choice was extended to six times the number of vacancies. Another Class I Departmental Promotion Committee met on October 22	 1971 and January 3	 1972. A third Class I Departmental Promotion Committee held its meetings on September 29 and 30	 1972	 and October 3	 1972. The Minutes of the several meetings indicate that the petitioners Nos. 1 to 8 were selected for officiating a appointments	 some of them being classified as "very goods" and others as "goods". They were accordingly appointed to officiate as Divisional Medical Officers on different dates in 1971 and 1972 and the petitioner No. 7	 the last to be promoted	 was appointed in 1974. The record shows that these were all regarded as officiating appointments to vacancies in the Class I posts of Divisional Medical Officers. There is nothing before us to indicate why the Railway Ministry sought to fill some of the vacancies in the permanent posts on a substantive basis and the others on an officiating basis. The respondents say that substantive appointments were made to permanent vacancies and officiating appointments were made to temporary vacancies. We have carefully perused the copies of the official documents placed on the record before us. They do not speak of temporary vacancies at all. Nor is there any material suggesting the need for treating some of the vacancies as temporary. There is nothing to show that the vacancies would have ceased to exist within the foreseeable future or upon the happening of some anticipated contingency. On the contrary	 the petitioners have continued to fill the vacancies for several years. In the circumstances we are of opinion that the vacancies to which the petitioners were appointed should be regarded as permanents vacancies. As regards the need for making officiating appointments	 it was explained during oral argument that officiating appointments were made when some of the candidates considered for substantive appointment were found to be of inferior calibre for such appointment	 and	 therefore	 some of the vacancies were left to be filled on 832 an officiating basis. We are not impressed by the submission. The communication of the Railway Ministry to the Departmental promotion Committee specifying the number and nature of the appointments to be made was issued long before the cases of individual officers were examined for promotion. It was only after the Departmental Promotion Committee had been informed of the Railway Ministry s requirement that it commenced its task of selecting candidates for substantive appointment and for officiating appointment. The field of choice for each category	 substantive appointment or officiating appointment	 was demarcated by the rule that the officers to be considered would be six times the number of vacancies. According to the material placed before us by the respondents	 the petitioners did not at any time fall within the field of choice for making substantive appointments. That was because their seniority in the grade of Assistant Medical Officers did not at the relevant time bring them within the field of choice for substantive appointment. They were considered for officiating appointment only	 and not for substantive appointment. It was the mere statistical fact of their seniority as Assistant Medical Officers	 and not there merit	 that precluded their consideration for substantive appointment as Divisional Medical Officers at the relevant time. Now the petitioners had been selected for promotion by the same or similar Class I Departmental Promotion Committees as those selecting the substantively appointed Divisional Medical Officers	 and in no sense were their functions and responsibilities any different from those of the substantively appointed Divisional Medical Officers. It seems to us that if from the outset the temporary vacancies had been regarded as permanent vacancies	 and substantive appointments had been made instead of officiating appointments	 the petitioners would have been appointed substantively to those permanent vacancies. In the entire field of choice in which they fall	 they were found to be the most meritorious. Ever since their respective appointments in 1971	 1972 and 1974 the petitioners have continued to serve without interruption as Divisional Medical Officers and were doing so when this writ petition was filed in 1981. They have continued to serve in the posts for a significant number of years	 and there is no indication that their appointments will come to an end merely because the vacancies have been described as temporary. There is no material to show that their confidential Records contained any adverse entries or that otherwise they were not fit on there merit for substantive appointment to permanent vacancies. Indeed	 we are told that the petitioners have now been appointed 833 Divisional Medical Officers on a substantive basis. It appears that the only reason why they were not originally appointed substantively to permanent vacancies as Divisional Medical Officers is that only a limited number of substantive appointments was desired by the Railway Ministry and the petitioners were not considered for these substantive appointments because they did not fall within the field of choice	 having regard to their place of seniority in the lower grade of Assistant Medical Officers. While there is no doubt that technically. according to the terms of appointment	 the petitioners were appointed on an officiating basis	 we are reminded of the observations of this Court in Baleshwar Prasad vs State of U.P "We must emphasis that while temporary and permanent posts have great relevancy in regard to the career of government servants	 keeping posts temporary for long	 sometimes by annual renewals for several years	 and denying the claims of the incumbents on the score that their posts are temporary makes no sense and strikes us as arbitrary	 especially when both temporary and permanent appointments are functionally identified. If in the normal course	 a post is temporary in the real sense and the appointee knows that his tenure cannot exceed the post in longevity	 there cannot be anything	 unfair of capricious in clothing him with no rights. Not so	 if the post is	 for certain depart mental or like purposes	 declared temporary	 but it is within the ken of both government	 and the appointee that the temporary posts are virtually long lived. It is irrational to reject the claim of the temporary appointee on the nominal score of the terminology of the post. We must also express emphatically that the principle which has received the sanction of this Court 's pronouncements is that officiating service in a post is for all practical purposes of seniority as good as service on a regular basis. " These are apposite observations bearing directly on the point before us. We may point out that they were found relevant by this Court 834 in deciding O.P. Singla vs Union of India. To our mind the petitioners are entitled to say that they should be considered at par for the purpose of fixing seniority	 with those appointed to permanent posts in a substantive capacity. Nothing has been placed before us to indicate why they should not be entitled to the benefits which the substantive holders of permanent posts enjoy. It seems to us that for the purpose of determining seniority among promotees the t petitioners should be treated as having been appointed to permanent vacancies from the respective date of their original appointment and the entire period of officiating service performed by them should be taken into account as if that service was of the same character as that performed by the substantive holders of permanent posts. As regards the practice on which the respondents have relied	 of maintaining the three lists A	 and that the petitioners were shown in List as being fit only for officiating promotion against a temporary vacancy	 it seems to us that the circumstance makes no difference to the view taken by us. We are of opinion that on the facts of this case	 when the petitioners are continuing to hold the posts of Divisional Medical Officers for several years	 the continued inclusion of their names in List is wholly meaningless. If it is true that the length of continuous service reckoned from the date of promotion furnishes the criterion for determining seniority between the petitioners and the substantively appointed Divisional Medical Officers	 that principle should apply with equal vigour as between the petitioners and those promotee respondents who also began to serve	 like the petitioners	 in officiating appointments as Divisional Medical Officers. There is no reason why such promotee respondents	 although appointed subsequently to the petitioners	 should be treated as senior to them. But it is said	 the date of confirmation is the material date for determining relative seniority	 and the promotee respondents were confirmed before the petitioners. It appears that the Railway administration in according confirmation has been influenced by two principal factors. One is that confirmation has been considered on zone wise. Confirmation has been made as vacancies have arisen within a particular zone. The vacancies differ from zone to zone. 835 They do not arise equally in different zones	 but turn on factors peculiar to each zone	 such as the strength of the cadre within the zone	 and the differing number of vacancies arising in different zones at different times. In other words	 confirmation based on the placement of an officer within a particular zone must necessarily be determined by factors confined to that zone and unrelated to an all India standard. It is apparent that confirmations limited by such a local perspective cannot serve as a legitimate base for drawing up a seniority list intended for effecting promotions to the all India cadre of Medical Superintendents. To adopt the date of confirmation as the governing point in such circumstances is to inject an element of inequality into the very foundation of the promotion process. I is conceivable that the Railway Administration has adopted the rule of according confirmations zone wise for certain practical considerations and	 therefore	 we do not propose to adjudicate on the validity of that practice. But we do lay down that such confirmations cannot legitimately constitute the basic norm for drawing up a seniority list of Divisional Medical Officers for the purpose of promotion to the grade of Medical Superintendents. In the circumstances	 the true principle	 in our opinion	 must be that seniority should be related to the length of continuous service as Divisional Medical Officers reckoned from the date of promotion to the post. This is subject of course to the exception that such service should not include any period served in a fortuitous	 stop gap or ad hoc appointment. Having said this	 we may advert now to the other factor which appears to have influenced the Railway administration in assigning seniority. The impugned seniority list was prepared in 1979. It was drawn up when the Rules of 1978 had come into force. It was drawn up at a time when the new rule of "non selection" embodied in the Rules of 1978. Or "seniority cum suitability" as the respondents understand it	 had begun to govern promotion to the grade of Divisional Medical Officers. The Railway administration	 following those rules	 ignored the fact that the petitioners had been selected on their merit to those posts long before	 and had occupied them all the years since. The consequence of applying the rule of seniority cum suitability in the lower grade was to wipe out all the advantage claimed by the petitioners by virtue of the several years of continuous service	 and to give an ascendancy to those Assistant Medical Officers who although promoted subsequently were confirmed earlier only by 836 reason of their seniority in the lower grade. The question is whether the rule of seniority cum suitability can prevail. The point would have been capable of easy resolution but for the complexity introduced in implementing the recommendations of the Third Pay Commission. The Third Pay Commission recommended an upward revision of the scale of pay attached to different grades of posts in the Railways. In the course of implementing the recommendation in relation to the Medical Department of the Railways	 the Railway Ministry issued a letter No. PC III/74/PS 1/2 dated December 31	 1974 publishing a schedule showing the revised scales of pay. The schedule contained a special provision in regard to the posts of Assistant Medical Officer. The entry read: Designation Authorised Existing rates Revised Revised rates of post Scale of of non Scale of non Pay Practising of Pay Practising allowance allowance (Rs.) (Rs.) (Rs.) Assistant 350 25 33 1/3% of 700 40 1 5 stages Medical 500 30 pay subject 900 EB Rs. 150/ Officer 590 EB to a minimum 40 1100 6 10 stages: 30 800 of Rs. 150/ 50 1250 Rs. 200/ EB 35 900 per month EB 50 (Class II) 1600 (Class I) 11 15 stages: Rs. 250/ 16th stage onwards: Rs. 300/ 650 30 1 8 stages: 740 35 Rs. 150/ 810 EB 35 880 40 1000 EB 9 13 stages: 40 1200 Rs. 200/ 14 16 stages: Rs. 250/p.m. Remarks: AMOs in the existing Class II scale of Rs. 350 900 will be screened to determine their fitness for the revised Class I scale of Rs. 700 1600 and only those found fit will be entitled to this revised Class I scale. Those not found fit will be entitled only to revised standard Class II scale of Rs. 650 1200 until they are found fit for Class I by the Screening Committee. Posts operated in the revised Class 837 I scale will be designated as "Assistant Divl. Medical Officer". Separate orders will be issued regarding the number of posts to be placed in each of the two scales from time to time. It is apparent that the post of Assistant Medical Officer originally carried the Class II scale of Rs. 350 900. That scale of pay was now substituted by two distinct scales of pay	 a higher scale of Rs. 700 1300 (Class I) and a revised lower scale of Rs. 650 1200 (Class II). Both scales of pay were shown against the posts of Assistant Medical Officer. The Class I scale of Rs. 700 1600 was intended for Assistant Medical Officer who were found fit by a Screening Committee for that scale	 and posts operating in that scale were designated as "Assistant Divisional Medical Officer". The Assistant Medical Officers not found fit by the Screening Committee were entitled only to the lower Class II scale of Rs. 650 1200 until they were subsequently found fit for the Class I scale by the Screening Committee. It is clear from the entry in the schedule that both groups of officers	 those drawing the Class I higher scale as well as those drawing the Class II lower scale	 were included under the single category "Assistant Medical Officer". All Assistant Medical Officers were screened in order to determine who among them were superior to the others for the purpose of meriting the higher of the two revised scales of pay. It was merely as a matter of convenience that Assistant Medical Officers who were allotted the higher revised scale were said to hold the posts designated as "Assistant Divisional Medical Officer Assistant"	 In short	 all the officers comprising the two groups were Assistant Medical Officers	 and an Assistant Divisional Medical Officer was nothing but an Assistant Medical Officer who drew the higher revised scale of pay. That being so	 the conclusion is inescapable that Assistant Divisional Medical Officers were	 for the purpose of promotion as Divisional Medical Officers	 governed by the Rules of 1965 and the Rules of 1973. Those Rules mention Assistant Medical Officers as a source of recruitment	 without referring to any limiting qualification that they should be officers drawing a Class II scale of pay. The expression "Assistant Medical Officer" in those Rules is comprehensive enough to include all Assistant Medical Officers	 whether drawing the Class II revised scale of pay or entitled to the Class I revised scale of pay. And all such Officers were	 under those Rules	 governed by the principle of selection on merit for promotion as Divisional 838 Medical Officers. It must be remembered that Assistant Medical Officers were designated as Assistant Divisional Medical Officers with effect from January 1	 1973	 when the Rules of 1965 were still in force. The Rules of 1973 came into force in August	 1973. It is true that when Assistant Medical Officers were designated as Assistant Divisional Medical Officers in the revised Class I scale of Rs. 700 1600 by a notification such as Notification No. E (GP) 74/1/153 dated July 24	 1976	 the notification spoke of the "appointment" of Class II Assistant Medical Officers as Assistant Divisional Medical Officers	 but having regard to the terms of the schedule to the Railway University 's letter dated December 31	 1974 referred to earlier	 such notification must be understood to mean that the Assistant Medical Officers had been assigned the Class I scale of Rs. 700 1600 and merely described as Assistant Divisional Medical Officers. As explained earlier	 they continued to belong to the broad category "Assistant Medical Officers". In this connection	 it is significant that upon Assistant Medical Officers being designated as Assistant Divisional Medical Officers under the new scheme	 there was no corresponding amendment in the Rules of 1965 or the Rules of 1973. It is for the first time	 under the Rules of 1978	 that we find that the post of Divisional Medical Officer is described as a "non selection" post to be filled by promotion from the ranks of Assistant Divisional Medical Officers and by direct recruitment. In other words	 the only Assistant Medical Officers now entitled to promotion as Divisional Medical Officers were those drawing the Class I scale of Rs. 700 1600 and designated as "Assistant Divisional Medical Officers". What is important to remember is that the new sub division of Assistant Medical Officers described as Assistant Divisional Medical Officers was deemed to have taken birth on January 1	 1973. five and a half years before the Rules of 1978 were brought into force. It could never have been intended that this class of officers should exist in a vacuum where no rules operated. There was no vacuum because they were comprehended within the expression "Assistant Medical Officer" in the Rules of 1965 and the Rules of 1973	 and therefore no amendment was considered necessary in those Rules to take cognizance of this class or sub division. We hold that the principle of selection by merit	 enunciated in the Rules of 1965 and the Rules of 1973 governed the promotion of Assistant Medical Officers (including Assistant Divisional Medical Officers) to the posts of Divisional Medical Officer before the Rules of 1978 came into force. Both before and after January 1	 1973	 839 during the period before the Rules of 1978 came into force	 the principle of "non selection"	 that is seniority cum suitability in the lower grade	 which was provided in the Rules of 1978 did not apply to the promotion of Assistant Medical Officers (including Assistant Divisional Medical Officers) to the posts of Divisional Medical officers. It is also beyond dispute that having regard to the provisions of the Rules of 1978	 those Rules can apply only to promotions and appointments to the posts of Divisional Medical Officers made under them	 that is from and after August 12	 1978. They cannot affect promotions and appointments already made before that date. And as the act of confirmation does not amount to a fresh appointment but merely to setting the seal of approval on an appointment already made	 it must follow that the Rules of 1978 cannot be applied for the purpose of confirming promotions and appointments made under the earlier Rules. Consequently	 upon all the considerations set forth earlier	 the confirmation of the petitioners and all other officers appointed to the posts of Divisional Medical Officer before the Rules of 1978 came into force must be governed by the Rules of 1965 and the Rules of 1973. It may be noted that promotions and appointments made under the Rules of 1965	 on the repeal of those rules by the Rules of 1973	 fall to be governed by the Rules of 1973	 for while repealing tho Rules of 1965 Rule 9 of the Rules of 1973 provides: "Provided that anything done or any action under the rules so repealed shall be deemed to have been done or taken under the corresponding provisions of these rules. " Significantly	 such a saving provision is absent in the Rules of 1978. this is as clear an indication as any that the scheme under the Rules of 1978 marked a complete departure from that embodied in the earlier Rules. We hold that the confirmation of the petitioners and other officers appointed as Divisional Medical Officers fall to be considered under the Rules of 1965 or the Rules of 1973 and not under the Rules of 1978. Accordingly	 the rule of seniority cum suitability cannot be applied to the petitioners and the promotee 840 respondents	 and all promotee respondents who were promoted to the posts of Divisional Medical Officer subsequent to the petitioners must be regarded as junior to them	 notwithstanding that they may have ranked senior to the petitioners in the grade of Assistant Medical Officers (including Assistant Divisional Medical Officers). This principle will rule even where confirmation is made zone wise	 for in the absence of anything adverse in the officer 's conduct	 quality of work or other relevant factor	 confirmation should follow the order in which the original appointments have been made. The respondents point out that the impugned Seniority List was prepared in 1979	 when the Rules of 1978 were in force	 and therefore the principle of seniority cum merit was made the basis of the Seniority List. It is immaterial	 in our opinion	 that the Seniority List was prepared in 1979. The inter se seniority between the members of a service will ordinarily depend on the date of entry into the grade. That is an event governed by the rales of recruitment	 whether it be direct recruitment or promotion on the basis of selection on merit or on the basis of seniority in the lower grade or some other factor. Where seniority is fixed in a grade according to the length of service in that grade	 that implies a reference back to the date of entry. It is wholly immaterial when the Seniority List is prepared. We approach the second part of this case now. The petitioners challenge the seniority assigned to the direct recruit respondents in the impugned Seniority List. They contend that the quota prescribed for direct recruitment and for promotion under the Rules has been wrongly applied at the stage of confirmation when it should have been applied at the stage of appointment. They also contend that there is no provision for applying the principle of rotation of vacancies between direct recruits and promotees for the purpose of determining relative seniority between them. And even if it can be said that the directive issued in 1976 constitutes a valid rule of rotation	 it is open to prospective operation only and cannot be applied retrospectively. Finally	 the petitioners urge that the promotees should be held entitled to a weightage of five years on the basis of their service in the Class II posts of Assistant Medical Officers when considering their seniority in relation to direct recruits. 841 The case of the respondents that the inter se seniority between the direct recruit and the promotee Divisional Medical Officers has been carefully fixed with reference to the direct recruitment and promotional quotas in force from time to time	 without affecting the date of confirmation of the Divisional Medical Officers. It is explained that where the promotees have been promoted in excess of their quota in a particular year	 they have to be pushed down to a later year for absorption when due within their quota	 and seniority has been fixed accordingly. It is pointed out that for some years direct recruitment could not be resorted to on the required scale as the restructuring of the Medical Department was under consideration with a view to improving the avenues of promotion. In consequence direct recruits appointed in later years were brought up higher in the Seniority List in order to provide them their due position according to the quota of vacancies laid down for direct recruitment. The respondents also point out that Divisional Medical Officers were allowed to count seniority only from the date of permanent absorption if such absorption was within their quota. It is stated that from 1973 onwards representations were made by and on behalf of promotees Divisional Medical Officers to give them weightage in respect of their officiating service for the purpose of seniority in the cadre of Divisional Medical Officers vis a vis the direct recruits	 and after giving due consideration to those representations and taking into regard the judgment of this Court in A. K. Subraman & Ors. etc. vs Union of India & Ors.	 it was decided that inter se seniority between direct recruit Divisional Medical Officers and promotee Divisional Medical Officers promoted permanently should be fixed on a rotational basis with reference to the direct recruitment and promotional quotas in force from time to time. It is maintained that the impugned Seniority List was prepared on the basis of those principles. The petitioners	 it is urged	 cannot claim inclusion in that list as none of them had been promoted as Divisional Medical Officers on a permanent basis against the quota of seats reserved for such promotions under the relevant Rules. The claim of the petitioners to a weightage of five years of substantive service rendered in the lower grade is disputed by the respondents on the ground that the principle providing such weightage for seniority has not been applied to the Medical Department of the Railways in view of the structural pattern of the Department. 842 The objection of the Respondents that the petitioners were not appointed to the posts of Divisional Medical Officers on a permanent basis and therefore they were not entitled to inclusion in the Seniority List can be disposed of shortly. We have already held while examining the case of the petitioners vis a vis the promotee respondents that the petitioners were entitled to be treated at par with substantively appointed Divisional Medical Officers for the purpose of fixing seniority	 and the circumstance that they were appointed in an officiating capacity was of no significance in this regard. We have pointed out that for determining seniority among promotees the petitioners should be treated as having been appointed to permanent vacancies from the respective dates of their original appointments and the entire period of their officiating service should be taken into account as if that service was of the same character as that performed by the substantive holders of permanent posts. We have held further that the promotee respondents appointed subsequently to the petitioners must be regarded as junior to them even though senior in the lower grade. We have detailed the reasons for taking this view. Applying the same criteria for determining the seniority between the petitioners and the direct recruits	 we are of opinion that the petitioners must be held senior to the direct recruits appointed subsequently to them. In this connection	 it would be permissible to quote from the judgment of this Court in O. P. Singla (Supra)	 where the question was of fixing seniority between temporary promotees and direct recruits: "Promotees	 who were appointed under Rule 16 have been officiating continuously	 without a break	 as Additional District and Sessions Judges for a long number of years. It is both unrealistic and unjust to treat them as aliens to the Service merely because the authorities did not wake up to the necessity of converting the temporary posts into permanent ones even after some of the promotees had worked in those posts from five to twelve years. The fact that temporary posts created in the Service under Rule 16(1) had to be continued for years on end shows that the work assigned to the holders of those posts was	 at least at some later stage	 no longer of a temporary nature. And yet instead of converting the temporary posts into permanent ones	 the authorities slurred over the matter and imperilled	 though unwittingly 843 the reasonable expectations of the promotees . . It is not fair to tell the promotees that they will rank as juniors to direct recruits who were appointed five to ten years after they have officiated continuously in the posts created in the Service and held by them	 though such posts may be temporary." And further: "The best solution to the situation which confronts us is to apply the rule which was adopted in S.B. Patwardhan vs State of Maharashtra ; It was held by this Court in that case that all other factors being equal	 continuous officiation in a non fortuitous vacancy ought to receive due recognition in fixing seniority between persons who are recruited from different sources	 so long as they belong to the same cadre	 discharge similar functions and bear the same responsibilities. Since the rule of 'quota and rota ' ceases to apply when appointments are made under Rule 16 and 17	 the seniority of direct recruits and promotees appointed under those Rules must be determined according to the dates on which direct recruit were appointed to their respective posts and the dates from which the promotees have been officiating continuously either in temporary posts created in the Service or in substantive vacancies to which they were appointed in a temporary capacity. " Considerable emphasis has been laid by the respondents on the fact that in the present case the pertinent Rules laid down the respective direct recruitment and promotional quotas from time to time	 and it was necessary to adjust the seniority between the direct recruit Divisional Medical Officers and the promotee Divisional Medical Officers in such a way that the quotas were maintained from year to year. This implied	 it is urged	 the rotation of vacancies between the two classes reserving them for one or the other in an order which would ensure compliance with the quotas. The Rules themselves do not lay down any principle of rotation. They specify the quotas only. It was for the first time on May 26/27	 1976 that the Railway Ministry by its letter No. E(O)I 74/SR 6/10 directed that "the seniority of Class II officers of the Medical Department	 844 promoted to Class I Senior Scale against the quota earmarked for a particular year vis a vis the officers recruited against the direct recruitment quota for that year will be fixed on a rotational basis with reference to the direct recruitment and promotional quotas in force from time to time. " This directive	 however	 can be of no assistance to the respondents. It may be open to an administration to work the quota rule through a principle of rotation	 but that implies that a quota rule is being actively operated and effect is being given to it. In the present case	 it must be borne in mind that the quotas laid down by the Rules were not observed at all by the Railway administration	 and no direct recruitment was made during the years 1973 to 1976. Indeed	 the process of direct recruitment was employed on a substantial basis only from 1978 onwards. Only one officer appears to have inducted by direct recruitment into the grade in 1977 and apparently none before. The grade of Divisional Medical Officers was manned by promotees selected on their merit under the Rules of 1965 and the Rules of 1973 There was power under Rule 7 of the Rules of 1973 to relax the provisions of those Rules	 which would include the provision requiring the observance of specified quotas for recruitment from promotional and from direct recruitment source It seems to us that the present case falls within the dicta of this Court in A. Janardhana vs Union of India and Others where the Court said: "We do propose to examine and expose an extremely undesirable	 unjust and inequitable situation emerging in service jurisprudence from the precedents namely	 that a person already rendering service as a promotee has to go down below a person who comes into service decades after the promotee enters the service and who may be a schoolian	 if not in embryo	 when the promotee on being promoted on account of the exigencies of service as required by the Government started rendering service." and concluded with the observations: "Even where the recruitment to a service is from more than one source and a quota is fixed for each service 845 yet more often the appointing authority to meet its exigencies of service exceeds the quota from the easily available source of promotees because the procedure for making recruitment from the market by direct recruitment is long	 prolix and time consuming. The Government for exigencies of service	 for needs of public services and for efficient administration	 promote persons easily available because in hierarchical service one hopes to move upward. After the promotee is promoted	 continuously renders service and is neither found wanting nor inefficient and is discharging his duty to the satisfaction of all	 a fresh recruit from the market years after promotee was inducted in the service comes and challenges all the past recruitments made before he was borne in service and some decisions especially the ratio in Jaisinghani case as interpreted in two B.S. Gupta cases gives him an advantage to the extent of the promotee being preceded in seniority by direct recruit who enters service long after the promotee was promoted. When the promotee was promoted and was rendering service	 the direct recruit may be a schoolian or college going boy. He emerges from the educational institution	 appears at a competitive examination and starts challenging everything that had happened during the period when he has had nothing to do with service . If this has not a demoralising effect on service we fail to see what other inequitous approach would be more damaging. It is	 therefore	 time to clearly initiate a proposition that a direct recruit who comes into service after the promotee was already unconditionally and without reservation promoted and whose promotion is not shown to be invalid or illegal according to relevant statutory or non statutory rules should not be permitted by any principle of seniority to secure a march over a promotee because that itself being arbitrary would be violative of Articles 14 and 16." In the present case	 there was no direct recruitment upto 1977 for certain administrative reasons	 and no observance of the quota system embodied in the prevailing Rules. The Assistant Medical Officers were pressed into service	 promoted as Divisional Medical 846 Officers and were alone responsible for assuming the burden and discharging the functions and duties of those posts during all the years until direct recruitment was made. It would be grossly unjust and discriminatory in the circumstances to require them to be junior to direct recruits brought in some years later. The respondents rely on A.K. Subraman (supra). In that case	 however	 the facts which the Court took into consideration and upon which it proceeded to render judgment were different. The point raised in the present case falls more appropriately within the scope of the observations in A. Janardhana (supra)	 to which elaborate reference has been made earlier. Indeed	 when A.K. Subraman (supra) was considered subsequently by this Court in P.S. Mahal vs Union of India the Court expressly referred to the exception implied in Bishan Sarup Gupta vs Union of India as the effect of a serious deviation from the quota rule	 and it recorded its agreement with A Janardhana (supra). It said: "But this rotational rule of seniority can work only if the quota rule is strictly implemented from year to year. Some slight deviations from the quota rule may not be material but as pointed out by Palekar	 J. in the Bishan Sarup Gupta case	 "if there is enormous deviation	 other considerations may arise". If the rotational rule of seniority is to be applied for determining seniority amongst officers promoted from different sources	 the quota rule must be observed. The application of the rotational rule of seniority when there is large deviation from the quota rule in making promotions is bound to create hardship and injustice and result in impetmissible discrimination. That is why this Court pointed out in A.K. Subraman case that '. when recruitment is from two or several sources it should be observed that there is no inherent invalidity in introduction of quota system and to work it out by a rule of rotation. The existence of a quota and rotational rule	 by itself	 will not violate Article 14 or Article 16 of the 847 Constitution It is the unreasonable implementation of the same which may	 in a given case	 attract the frown of the equality clause. ' (SCC para 28	 p.333:SCC (L&S) p.50) The rotational rule of seniority is inextricably linked up with the quota rule and if the quota rule is not strictly implemented and there is large deviation from it regularity from year to year	 it would be grossly discriminatory and unjust to give effect to the rotational rule of seniority. We agree wholly with the observation of D.A. Desai	 J. in A Janardhana vs Union of India that '. where the quota rule is linked with the seniority rule if the first breaks down or is illegally not adhered to giving effect to the second would be unjust	 inequitous and improper. ' (SCC para 29	 p.621 :SCC (L&S) p. 487) This was precisely the reason why the Court in the first Bishan Sarup Gupta case held that with the collapse of the quota rule	 the rule of seniority set out in Rule 1 (f) (iii) also went. " In our opinion	 the directly recruited Divisional Medical Officers are entitled to seniority only from the date of their entry into service and not from any anterior date	 and therefore cannot enjoy a seniority above the petitioners. The date of appointment to a permanent vacancy	 whether of a promotee or a direct recruit	 will be the date for determining the seniority of the officer. We may also observe that there is no ground for detaining the confirmation of the petitioners merely because the quota reserved for direct recruitment has not been filled. As regards the claim to weightage made by the petitioners on the basis of their service in the lower grade of Assistant Medical Officers	 we find no substance in the claim because the administrative instructions issued under the Railway Board 's letter No. E.54/SR 6/1/2 dated March 10	 1955	 on which the petitioners rely	 did not apply to the Medical Department of the Railways. In the result	 the writ petition is allowed	 the Seniority List published by the Railway Ministry 's letter No. 752 E/530 (E1A) 848 dated November 22	 1979 as well as the appointments made to the posts of Medical Superintendents by the Railway Ministry 's letter No. E(O)III 81 PM6/199 dated August 31	 1981 are quashed. The Railway administration is directed to draw up a fresh Seniority List of Divisional Medical Officers in accordance with the principles laid down in the judgment and to make fresh appointments from among the Divisional Medical Officers to the posts of Medical Superintendents. The petitioners are entitled to their costs against respondents Nos. 1	 2 and 3. A.P.J. Petition allowed.

The Indian Railways Medical Service consists of Assistant Divisional Medical Officers Class I (before January 1	 1973 described as Assistant Medical Officers Class II)	 Divisional Medical Officers	 Medical Superintendents	 Chief Medical Officers and Director General of Medical Services. The Petitioners in the writ petition who were Assistant Medical Officers Class II were confirmed	 one in 1962 and the others in 1963. During the years 1970 to 72 they were selected by Departmental Promotion Committees for officiating appointments to the Class I post of Divisional Medical Officers. At that time the Indian Railway Medical Service (District Medical Officers) Recruitment Rules 1965 were applicable. Those Rules were repealed and replaced by the Indian Railway Medical Service (District Medical Officers) Recruitment Rules 1973. Under the Rules of 1965 and the Rules 1973 the posts of District Medical Officers were treated as selection posts. 819 The existing pay scale of Rs. 350 900 attached to the post of Assistant Medical Officer was revised by the Third Pay Commission and split into two A pay scales	 a higher Class I scale of Rs. 700 1600 and a lower Class II scale of Rs. 650 1200 and the posts of Assistant Medical Officers were divided into those carrying the higher pay scale and those carrying the lower pay scale. The upgraded posts in the higher pay scale of Rs. 700 1600 were designated as "Assistant Divisional Medical Officers". The petitioners were placed in the higher pay scale of Rs. 700 1600 and were designated as Assistant Divisional Medical Officers with effect from January 1	 1973. The Rules of 1973 were replaced by the Indian Railway Medical Service (Divisional Medical Officers/Senior Medical Officers) Recruitment Rules 1975	 which were further replaced by the Indian Railway Medical Service (Chief Medical Officers	 Additional Chief Medical Officers	 Medical Superintendents and Divisional Senior Medical Officers) Recruitment Rules	 1978. Under these Rules promotion is effected on the principle of "non selection"	 that is	 on "seniority cum suitability" basis. The Rules of 1965 showed that there were 101 posts in the grade of Divisional Medical Officers. The Rules of 1973 mentioned 109 posts and referred to them as permanent posts only. The Railway Ministry for the promotion of Assistant Medical Officers to the Class I posts of Divisional Medical Officers indicated the number of anticipated vacancies for the purpose of permanent promotion and the number of anticipated vacancies for the purpose of officiating appointments	 the number under each category being specified zone wise. A Class I Departmental Promotion Committee met on several occasions and considered the cases of candidates who had completed five years and above of service as Assistant Medical Officers for substantive promotion and for officiating promotion	 the field of choice being extended to six times the number of vacancies. The petitioners were selected on the basis of merit and appointed to officiate as Divisional Medical Officers on different dates in 1971 and 1972	 except petitioner No. 7 who was promoted and appointed in 1974. The Railway Board on October 30	 1979 published a combined seniority list of Divisional Medical Officers recruited directly or by promotion. Respondents Nos. 4 to 64 included both promotees and direct recruits and were shown in that list. The petitioners did not find place in the seniority list. Subsequently on the basis of that seniority list	 some of the respondent Divisional Medical Officers were appointed on August 31	 1934 to of officiate as Medical Superintendents. In the Writ Petition under article 32 the petitioners challenged the validity of the combined seniority list dated 30th October	 1979 of Divisional Medical Officers and of the officiating promotions to the posts of Medical Superintendents as violative of articles 14 and 16 of the Constitution	 contending: that they were promoted as Divisional Medical Officers much earlier than the promotee respondents; that their promotion was made by selection on the basis of merit 820 adjudged by the Departmental Promotion Committees under the Rules of 1965; that they had continued in service as Divisional Medical Officers against vacancies in permanent posts without interruption for periods ranging between 8 years to 12 years	 and that the promotee respondents	 who had held such posts for shorter periods	 had been confirmed before the petitioners and shown senior in the seniority list and preferred for promotion as Medical Superintendents; that the petitioners should have been confirmed in the normal course; that the promotee respondents have been confirmed zone wise	 and such confirmation cannot serve as a proper reference for determine seniority because when confirmation is granted zone wise	 it depends on the fortuitous accrual of vacancies arising arbitrarily at different times and in different numbers in different individual zones; that if the date of confirmation is adopted as the criterion	 confirmation should not be reckoned on a zonal basis. Promotion to the post of Medical Superintendents	 which is an all India cadre post should properly be drawn on an All India basis and that if confirmation has to be considered zone wise then for the purpose of promotion to the all India cadre of Medical Superintendents the only logical and uniform criterion should be the total length of continuous service as Divisional Medical Officers reckoned from the date of promotion; that for the purpose of fixing seniority in the grade of Divisional Medical Officers the seniority in the grade OF Assistant Medical Officers or Assistant Divisional Medical Officers is of no material significance because under the Rules in force when the promotion in the instant case were made	 the petitioners were governed by the principle of selection on the basis of merit; that the quota prescribed for direct recruitment and for promotion under the Rules has been wrongly applied at the stage of confirmation when it should have been applied at the stage of appointment and that there is no provision for applying the principle of rotation of vacancies between direct recruits and promotees for the purpose of determining relative seniority between them. The respondents	 however contended: that the seniority list has been correctly prepared	 it contains the names of only those officers who were either directly recruited as Divisional Medical Officers or had been approved for permanent promotion against the quota of posts reserved for them in vacancies allotted among the individual Railways on the basis of the cadre position of each Railway	 and that none of the petitioners qualified for inclusion in the seniority list as they had been promoted in an officiating capacity to temporary vacancies in the posts of Divisional Medical Officers; that the petitioners have no right to be treated at par with those officers who were holding permanent posts on a confirmed basis	 as confirmation was made on the basis of their selection for permanent promotion as Divisional Medical officers and their seniority was also fixed on that basis. According to the practice followed by the Railway Administration three select lists were prepared. List A set out the names of officers selected for substantive promotion against permanent vacancies. List included the names of officers selected for officiating promotion against temporary vacancies. The petitioners were placed in List B. The third list. List C	 bore the names of officers included in List by earlier Depart mental Promotion Committees but not considered as "suitable yet" for substantive promotion by subsequent Departmental Promotion Committees. The inter se seniority between the direct recruit and the promotee Divisional Medical 821 Officers has been carefully fixed with reference to the direct recruitment and promotional quotas in force from time to time	 without affecting the date of confirmation of the Divisional Medical Officers. The petitioners cannot claim inclusion in the impugned seniority list as none of them had been promoted as Divisional Medical Officers on a permanent basis against the quota of seats reserved for such promotions under the relevant Rules	 and cannot get weightage of five years of substantive service rendered in the lower grade because the principle providing such weightage for seniority has not been applied to the Medical Department of the Railways. Allowing the petition	 ^ HELD: 1. The seniority list published by the Railway Ministry 's letter No. 752 E/530 (EI A) dated November 22	 1979 as well as the appointments made to the posts of Medical Superintendents by the Railway Ministry 's letter No. E(O) III 81 PM6 199 dated August 31	 1981 are quashed. The Railway Administration is directed to draw up a fresh Seniority List of Divisional Medical Officers and to make fresh appointments from among Divisional Medical Officers to the posts of Medical Superintendents. [847 H; 848 A B] 2. There is nothing to indicate why the Railway Ministry sought to fill some of the vacancies in the permanent posts on a substantive basis and the others on an officiating basis. The explanation offered is that substantive appointments were made to permanent vacancies and officiating appointments were made to temporary vacancies. The documents on record do not speak of temporary vacancies at all. There is no material suggesting the need for treating some of the vacancies as temporary and to show that some vacancies would have ceased to exist within the foreseeable future or upon the happening of some anticipated contingency On the contrary	 the petitioners had continued to fill the vacancies to which the petitioners were appointed should be regarded as permanent vacancies. [831 D G] 3. The explanation that officiating appointments were made when some of the candidates considered for substantive appointment were found to be of inferior calibre for such appointment and	 therefore	 some of the vacancies were left to be filled on an officiating basis is not plausible. The communication of the Railway Ministry to the Departmental Promotion Committee specifying the number and nature of the appointments to be made was issued long before the cases of individual officers were examined for promotion. It was only after the Departmental Promotion Committee had been informed of the Railway Ministry 's requirement that it commenced its task of selecting candidates for substantive appointment and for officiating appointment. The material produced by the respondents shows that the petitioners did not at any time fall within the field of choice for making substantive appointments. That was because their seniority in the grade of Assistant Medical Officers did not at the relevant time bring them within the field of choice for substantive appointment. They were considered for officiating appointment only	 and not for substantive 822 appointment. It was the mere statistical fact of their seniority as Assistant Medical Officers	 and not their merit	 that precluded their consideration for substantive appointment as Divisional Medical Officers at the relevant time. [831 H; 832 A D] 4. If from the outset the temporary vacancies had been regarded as permanent vacancies	 and substantive appointments had been made instead of officiating appointments	 the petitioners would have been appointed substantively to those permanent vacancies. In the entire field of choice in which they fall	 they were found to be the most meritorious. Ever since their respective appointments in 1971	 1972 and 1974 the petitioners have continued to serve without interruption as Divisional Medical Officers and were doing 50 when this writ petition was filed in 1981. They have continued to serve in the posts for a significant number of years	 and there is no indication that their appointments will come to an end merely because the vacancies have been described as temporary. There is no material to show that their confidential Records contained any adverse entries or that otherwise they were not fit on their merit for substantive appointment to permanent vacancies. The petitioners have now been appointed Divisional Medical Officers on a substantive basis. The only reason why they were not originally appointed substantively to permanent vacancies as Divisional Medical Officers is that only a limited number of substantive appointments was desired by the Railway Ministry and the petitioners were not considered for those substantive appointments because they did not fill within the field of choice	 having regard to their place of seniority in the lower grade of Assistant Medical Officers. [832 F H; 833 A B] 5. The petitioners are entitled to say that they should be considered at par	 for the purpose of fixing seniority	 with those appointed to permanent posts in a substantive capacity. There is nothing to indicate why they should not be entitled to the benefits which the substantive holders of permanent posts enjoy. For the purpose of determining seniority among promotees the petitioners should be treated as having been appointed to permanent vacancies from the respective dates of their original appointment and the entire period of officiating service performed by them should be taken into account as if that service was of the same character as that performed by the substantive holders of permanent posts. [834 A C] Baleshwar Prasad vs State of UP.	[1981] 1 S.C.R. 449	 462 and O.P. Singla vs Union of India	 	 followed. In the instant case	 as the petitioners are continuing to hold the posts of Divisional Medical Officers for several years	 the inclusion of their names in List is wholly meaningless. [834 D] 7. If length of continuous service reckoned from the date of promotion furnishes the criterion for determining seniority between the petitioners and the substantively appointed Divisional Medical Officers	 that principle should apply 823 with equal vigour as between the petitioners and those promotee respondents who also began to serve	 like the petitioners	 in officiating appointments as Divisional Medical Officers. There is no reason why such promotee respondents	 although appointed subsequently to the petitioners	 should be treated as senior to them. [834 F] 8. The date of confirmation is the material date for determining relative seniority. The Railway administration in according confirmation has been influenced by two principle factors. One is that confirmation has been considered zone wise. Confirmation has been made as vacancies have arisen within a particular zone. The vacancies differ from zone to zone. They no not arise equally in different zones but turn on factors peculiar to each zone	 such as the strength of the cadre within the zone	 and the differing number of vacancies arising in different zones at different times. In other words	 confirmation based on the placement of an officer within a particular zone must necessarily be determined by factors confined to that zone and unrelated to an all India standard. It is apparent that confirmations limited by such a local perspective cannot serve as a legitimate base for drawing up a seniority list intended for effecting promotion	 to the all India cadre of Medical Superintendents. To adopt the date of confirmation as the governing point in such circumstances is to inject an element of inequality into the very foundation of the promotion process. It is conceivable that the Railway Administration has adopted the rule of according confirmations zone wise for certain practical consideration and the validity of that practice need not be adjudicated on. But such confirmations cannot legitimately constitute the basic norm for drawing up a seniority list of Divisional Medical Officers for the purpose of promotion to the grade of Medical Superintendents. The principle must be that seniority should be related to the length of continuous service as Divisional Medical Officers reckoned from the date of promotion to the post; such service should not include any period served in a fortuitous	 stop gap or adhoc appointment. [834 G H; 835 A E] 9. After implementation of the recommendations of the Third Pay Commission	 all the officers comprising the two groups were Assistant Medical Officers	 and an Assistant Medical Officer was nothing but as Assistant Medical Officer who drew the higher revised scale of pay. The conclusion is inescapable that Assistant Divisional Medical Officers were	 for the purpose of promotion as Divisional Medical Officers	 governed by the Rules of 1965 and the Rules of 1973. Those Rules mention Assistant Medical Officers as a source of recruitment	 without referring to any limiting qualification that they should be officers drawing a Class II scale of pay. The expression "Assistant Medical Officer" in those Rules is comprehensive enough to include all Assistant Medical Officers	 whether drawing the class II revised scale of pay or entitled to the Class I revised scale of pay. And all such Officers were	 under those Rules	 governed by the principle of selection on merit for promotion as Divisional Medical Officers. The Assistant Medical Officers were designated as Assistant Divisional Medical Officers with effect from January 1	 when the Rules of 1965 were still in force The Rules of 1973 came into force in August	 1973. It is true that when Assistant Medical Officers were designated as Assistant Divisional Medical Officers in the revised Class I scale of Rs. 700 1600 by 824 Notification No. E(GP) 74/1/153 dated July 24	1976	 the notification spoke of the "appointment" of Class II Assistant Medical Officers as Assistant Divisional Medical Officers	 but having regard to the terms of the schedule to the letter dated December 31	 1974 such notifications must be understood to mean that the Assistant Officers had been assigned the Class I scale of Rs. 700 1600 and merely described as Assistant Divisional Medical Officers. They continued to belong to the broad category of "Assistant Medical Officers". Upon Assistant Medical Officers being designated as Assistant Divisional Medical Officers under the new scheme	 there was no corresponding amendment in the Rules of 1965 or the Rules of 1973. It is for the first time	 under the Rules of 1978	 that the post of Divisional Medical Officer is described as a "non selection" post to be filled by promotion from the ranks of Assistant Divisional Medical Officers and by direct recruitment. The only Assistant Medical Officers now entitled to promotion as Divisional Medical Officers were those drawing the Class I scale of Rs 700 1600 and designated as Assistant Divisional Medical Officers". The new sub division of Assistant Medical Officers described as Assistant Divisional Medical Officers was deemed to have taken birth on January 1	 1973 five and a half years before the Rules of 1978 were brought into force. It could never have been intended that this class of Officers should exist in a vacuum where no rules operated. There was no vacuum because they were comprehended within the expression "Assistant Medical Officer" in the Rules of 1965 and the Rules of 1973	 and therefore	 no amendment was considered necessary in those Rules to take congnisance of this class. [837 E H; 838 A G] 10. The principle of selection by merit	 enunciated in the Rules of 1965 and the Rules of 1973 governed the promotion of Assistant Medical Officers (including Assistant Divisional Medical Officers) to the posts of Divisional Medical Officer before the Rules of 1978 came into force Both before and after January 1	 1973	 during the period before the Rules of 1978 came into force the principle of "non selection"	 that is seniority cum suitability in the lower grade	 which was provided in the Rules of 1978 did not apply to the promotion of Assistant Medical Officers (including Assistant Divisional Medical Officers to the posts of Divisional Medical Officers. [838 G H; 839 A] 11. The confirmation of the petitioners and all other officers appointed to the posts of Divisional Medical Officer before the Rules of 1978 came into force must be governed by the Rules of 1965 and the Rules of 1973. The promotions and appointments made under the Rules of 1965	 on the repeal of those rules by the Rules of 1973	 fall to be governed by the Rules of 1973. [839 D E] 12. The inter se seniority between the members of a service will ordinarily depend on the date of entry into the grade. That is an event governed by the Rules of recruitment	 whether it be direct recruitment or pro motion on the basis of selection on merit or on the basis of seniority in the lower grade or some other factor. Where seniority is fixed in a grade according to the length of service in that grade	 that implies a reference back to the date of entry. It is wholly immaterial when the seniority list is prepared. [840 C E] In the instant case	 applying the criteria for determining seniority vis a vis the promotee respondents and the petitioners to the case of petitioners and the 825 direct recruits	 the petitioners must be held senior to the direct recruits appointed subsequently to them. [842 D E] O.P. Singla vs Union of India	 	 followed. The rules themselves do not lay down any principle of rotation. They specify the quotas only. It was for the first time on May 26/27	 1976 that the Railway Ministry by its Letter No E(O) I 74/SR 6/10 directed that the seniority of Class II officers of the Medical Department	 promoted to Class I Senior Scale against the quota earmarked for a particular year vis a vis the officers recruited against the direct recruitment quota for that year will be filed on a rotational basis with reference to the direct recruitment and promotional quotas in force from time to time. " This directive	 however	 can be of no assistance to the respondents. It may be open to an administration to work the quota rule through a principle of rotation	 but that implies that a quota rule is being actively operated and effect is being given to it. In the present case	 the quotas laid down by the Rules were not observed at all and no direct recruitment was made	 during the years 1973 to 1976. Indeed	 the process of direct recruitment was employed on a substantial basis only from 1978 onwards. There was power under Rule 7 of the Rules of 1973 to relax the provisions of those rules	 which would include the provision requiring the observance of specified quotas for recruitment from promotional and from direct recruitment sources. [843 G H; 844 A D] A. Janardhana vs Union of India & Ors.	 [1983] 3 S.C.C. 601	 followed	 and A.K. Subraman & Ors. etc. vs Union of India & Ors.	 [1975] 2 S.C.R. 979 inapplicable. P.S. Mahal vs Union of India	 ; and Bishan Sarup Gupta vs Union of India	 [1975] Supp. S.C.R 491	 referred to. [847 E] 14. The directly recruited Divisional Medical Officers are entitled to seniority only from the date of their entry into service and not from any anterior date	 and therefore cannot enjoy seniority above the petitioners.