Summarize the following court judgment. Civil Appeal Nos.4255 57 of 1992. From the Judgment and order dated 15.10.1991	28.11.1991 and 17.12.1991 of Madhya Pradesh Administrative Tribunal	 Jabalpur in O.A.Nos. 140 of 1990 and 3024 of 1991 and T.A. No.35 of 1988. U.N. Bachawat	 B.S. Banthia	 G. Prakash	 L.C. Agrawala	 K.K. Chagotra and Indra Makwana for the Appellants. S.S. Ray	 A. Raghuvir	 A.K. Sen. Dr. N.M. Ghatate	 S.K. Gambhir	 Vivek Gambhir	 S.K. Jain	 A.P. Dhamija	 R.B. Misra	 N.D.B. Raju	 Anand Prasad	 S.V. Deshpande and S.K. Agnihotri for the Respondents. The Judgments of the Court was delivered by KASLIWAL	 J. Special leave granted in all the above cases. All the above appeals are disposed of by a common order	 as identical questions of law are involved in these cases. For the purpose of understanding the controversy raised in all these cases	 we are stating the facts of appeal arising out of special leave petition No. 2507 of 1992. The appellants and the private respondents were Sub Engineers in Public Health Engineering Department of Government of Madhya Pradesh. They are governed by Madhya Pradesh Public Health Engineering (Gazetted) Service Rules 1980 (hereinafter referred to as `the Rules '). Under Schedule IV of the Rules	 the next higher post for promotion from the post of Sub Engineers in Civil or Mechanical is the post of Assistant Engineers. The minimum period for Sub Engineer to qualify for promotion to the post of Assistant Engineer is 12 years for diploma holders and 8 years for such Sub Engineers who obtain degree of graduation in the course of service. Earlier 60 per cent quota for the posts of Assistant Engineers was fixed by direct recruitment and 40 percent by promotion from the Sub Engineers	 Draftsman and Head Draftsman. By and executive order dated 7.2.1989	 quota of direct recruitment was reduced to 50 percent and the quota by promotion increased to 50 per cent. This 50 per cent quota by promotion with which we are concerned in the above cases has been sub divided in the following manner: (i) Diploma holder Sub Engineers completing 12 years of service 35% (ii) Draftsman & Head Draftsman completing 12 years of service 5% (iii) Graduate Sub Engineers completing 8 years of service 10% In the above cases we are now concerned with the third category of cases which deal with the promotion of Graduate Sub Engineers Completing 8 years of service. The State Government had been applying the principle of counting the seniority of Graduate Sub Engineers from the date of their continuous officiation irrespective of the date on which such diploma holder Sub Engineer acquired degree of graduation in engineering. On this basis	 the Departmental promotion Committee took into consideration 30 Graduate Sub Engineers for promotion to the post of Assistant Engineers. The D.P.C. by order dated 4.12.1989 prepared a panel of 18 Graduate Sub Engineers found suitable for promotion to the post of Assistant Engineer. The Government by order dated 6.12.1989 promoted M.B. Joshi and six others as Assistant Engineer who are appellants in appeal arising out of special leave petition No. 2507 of 1992. The private respondents in this appeal filed application No. 140/90 in Madhya Pradesh Administrative Tribunal	 Jabalpur challenging the aforesaid orders dated 4.12.1989 and 6.12.1989. The contention of these persons before the Tribunal was that the seniority for the purpose of promotion to the post of Assistant Engineers in 10 per cent quota of Graduate Sub Engineers completing 8 years of service ought to have been considered from the date of attaining the Graduate degree of engineering and not from the date of appointment as sub Engineer. The Tribunal placing reliance on its earlier decision in T.A. No. 771/88 Sanaulla Sunzani vs State of M.P. & 5 others	 held that the seniority of diploma holder Sub Engineers acquiring the degrees of graduation in engineering for inclusion in the gradation list of Sub Engineers should be counted from the dates of acquisition of graduation in engineering or of any other equivalent degree and not from the dates of their initial entries as Sub Engineers. Applying to aforesaid principle laid down in Sanaulla 's case	 the Tribunal held that the applicants (private respondents in the appeal) having secured the degrees in engineering prior to respondents 3 to 9 (the appellants in the appeal) will rank higher in the gradation list of Graduate Sub Engineers. The Tribunal as such allowed the petition filed before them and directed the State Government and Engineer in Chief	 Public Health Engineering Department to convene a special D.P.C. to consider applicants for promotion to the post of Assistant Engineers as on 4.12.1989 and if found suitable for promotion	 promote them and give them seniority over respondents 3 to 9 within 4 months of the date of receipt of the order. The short controversy arising in these cases relates to the determination of seniority amongst the diploma holder Sub Engineers who acquired the degree of graduation in engineering during the period service qualifying them for promotion in 8 years to the post of Assistant Engineer. It is an admitted position that there is no specific rule governing such situation. Relevant extracts of Schedule IV of the Rules as published in the Madhya Pradesh Gazette dated 27.2.1981 issued in Hindi read as under: Mr. S.S. Ray	 learned senior counsel appearing on behalf of the appellants contended that so far as the post of Sub Engineers is concerned	 the minimum qualification prescribed is diploma holder. Initially	 in the Public Health Engineering Department till 1980	 fresh degree holders used to get job directly as Assistant Engineers and the diploma holders used to be appointed as Sub Engineers. Thereafter on account of unemployment	 the degree holders also started seeking appointments as Sub Engineers. However	 so far as the post of sub Engineer was concerned	 the seniority was determined on the basis of the date of appointment on the post of Sub Engineer irrespective of the fact that the person joining such post was a degree holder or a diploma holder. The scale of pay was similar and the diploma holder and degree holder Sub Engineers stood on the same footing and their gradation list was prepared on the basis of length of service in the cadre of Sub Engineers. The next higher post for promotion from the post of Sub Engineer is the post of Assistant Engineer. Every diploma holder sub Engineer became eligible for promotion to the post of Assistant Engineer after having completed 12 years of service. The Government however	 considered it proper to reduce this period of 12 years to 8 years in case of such diploma holder Sub Engineers who obtained a degree of engineering during the continuance of their service as Sub Engineer as a sort of incentive to improve the qualification while continuing in service. It was thus	 submitted by Mr. Ray that it is a well settled principle of service jurisprudence that where the rules are silent	 the seniority is always determined on the basis of length of service amongst the employees appointed on a similar post in the same cadre. It was thus	 submitted that obtaining a degree during the continuation of service as Sub Engineer simply accelerated the entitlement to promotion for the post of Assistant Engineer from 12 years to 8 years but it did not in any manner disturb the seniority which was already settled on the basis of length of service on the post of Sub Engineer. It was submitted that the D.P.C. rightly prepared the panel of selection and the Government took a correct decision in issuing the order dated 6.12.1989. Mr. Ashok Sen	 learned senior counsel appearing on behalf of the respondents contended that it was necessary to obtain the degree of engineering for being qualified for promotion to the post of Assistant Engineer within a period of 8 years instead of 12 years. It was further argued that the period of 8 years can only be counted from the date when the diploma holder Sub Engineer acquired the degree of engineering and not prior to said date. Mr. Sen further placed reliance on N. Suresh Nathan & Another vs Union of India & Others	 [1992] Supp.1 SCC 584	 and submitted that this case clinches the issue raised in these cases and is no longer open for consideration. We have given our careful consideration to the arguments advanced on behalf of learned counsel for the parties. We may first deal with N. Suresh Nathan 's case (supra) on which strong reliance is placed by Mr. Ashok Sen. In this case	 the Recruitment Rules for the post of Assistant Engineer in the Public Works Department	 Pondicherry	 prescribing the educational and other qualifications for appointment by direct recruitment and promotion came for consideration. For direct recuits	 the qualification prescribed was a Degree in Civil Engineering of a recognised University or Diploma in Civil Engineering from a recognised institution with three years	 professional experience. For appointment by promotion of Section Officers now called junior Engineers	 the qualification prescribed was as under: "1. Section Officers possessing a recognised Degree in Civil Engineering or equivalent with three years ' service in the grade failing which Section Officers holding Diploma in Civil Engineering with six years ' service in the grade 50 percent. Section Officers possessing a recognised Diploma in Civil Engineering with six years ' service in the grade 50 per cent. " The dispute in the above case was whether a diploma holder Junior Engineer who obtains a degree while in service becomes eligible for appointment as Assistant Engineer by promotion on completion of three Years ' service including therein the period of service prior to obtaining the degree or the three years ' service including therein the period of service prior to obtaining the degree or the three years ' service as a degree holder for this purpose is to be reckoned from the date he obtains the degree. The Central Administrative Tribunal held that the applicants diploma holders were entitled to be considered for promotion to the post of Assistant Engineer on par with the other degree holder Junior Engineers taking due note of their total length other degree holder junior Engineers taking due note of their total length of service rendered in the grade of Junior Engineers taking due note of their total length of service rendered in the grade of grade of junior of Junior Engineer. Such a consideration should be alongside other Junior Engineers who might have acquired the necessary degree qualification earlier than the applicants	 while holding the post of Junior Engineer. This Court allowed the appeal and set aside the above order of the Tribunal. While allowing the appeal	 this Court held as under: "In our opinion	 this appeal has to be allowed. There is sufficient material including the admission of respondents diploma holders that the practice followed in the department for a long time was that in the case of diploma holder Junior Engineers who obtained the degree during service	 the period of three years ' service in the grade for eligibility for promotion as degree holders commenced from the date of obtaining the degree and the earlier period of service as diploma holders was not counted for this purpose. This earlier practice was clearly admitted by the respondents diploma holders in para 5 of their application made to the Tribunal at page 115 of the paper book. This also appears to be the view of the Union Public Service Commission contained in their letter dated December 6	 1968 extracted at pages 99 100 of the paper book in the counter affidavit of respondents 1 to 3. The real question	 therefore	 is whether the construction made of this provision in the rules on which the past practice extending over a long period is based is untenable to require upsetting it. If the past practice is based on one of the possible constructions which can be made of the rules then upsetting the same now would not be appropriate. It is in this perspective that the question raised has to be determined." This Court then considered the Recruitment Rules applicable in the said case and then held that the entire scheme did indicate that the period of three years ' service in the grade required for degree holders according to Rule 11 as the qualification for promotion in that category must mean three years ' service in the grade as a degree holder	 and therefore	 that period of three years can commence only from the date of obtaining the degree and not earlier. It was further held that the service in the grade as a diploma holder prior to obtaining the degree cannot be counted as service in the grade with a degree for the purpose of three years ' service as a degree holder. This Court then observed: "In our opinion	 the contention of the appellants degree holders that the rules must be construed to mean that the three years ' service in the grade of a degree holder for the purpose of Rule 11 is three years from the date of obtaining the degree is quite tenable and commends to us being in conformity with the past practice followed consistently. It has also been so understood by all concerned till the raising of the present controversy recently by the respondents. The Tribunal was	 therefore	 not justified in taking the contrary view and unsettling the settled practice in the department." A perusal of the above observations made by this Court clearly show that the respondents diploma holders in that case had admitted the practice followed in that department for a long time. It was clearly laid down in the above case that if the past practice is based on one of the possible constructions which can be made of the rules then upsetting the same now would not be appropriate. It was clearly said "it is in this perspective that the question raised has to be determined. " It was also observed as already quoted above that the Tribunal was not justified in taking the contrary view and unsettling the settled practice in the department. That apart the scheme of the rules in N. Suresh Nathan 's case was entirely different from the scheme of the Rules before us. The rule in that case prescribed for appointment by promotion of Section Officers/Junior Engineers provided that 50 per cent quota shall be from Section Officers possessing a recognised degree in Civil Engineering or equivalent with three years ' service in the grade failing which Section Officers holding Diploma in Civil Engineering with six years ' service in the grade. The aforesaid rule itself provided in explicit terms that Section Officers possessing a recognised Degree in Civil Engineering was made equivalent with three years ' service in the grade. Thus	 in the scheme of such rules the period of three years ' service was rightly counted from the date of obtaining such degree. In the cases in hand before us	 the scheme of the rules is entirely different. In the cases before us 50 per cent of the posts of Assistant Engineers has to be filed by direct recruitment of persons having degree of graduation in engineering. The remaining 50 per cent of the vacant posts are to be filled by promotion from the lower cadre of sub Engineer and Draftsman. Out of this 50 per cent	 35 per cent quota is fixed for diploma holders who have completed 12 years of service on the post of sub Engineer	 5 percent quota for Draftsman who have completed 12 years of service and the remaining 10 per cent with which we are concerned has been kept for such Sub Engineers who during the continuation of their service obtained a degree of graduation or equivalent in engineering and in that case the period of service is reduced from 12 from 8 years. The Rules in our case do not contemplate any equivalence of any period of service with the qualification of acquiring degree of graduation in engineering as was provided in express terms in N. Suresh Nathan 's case making three years service in the grade equivalent to degree in engineering. In our opinion	 in the rules applicable in the cases before us clearly provide that the diploma holders having obtained a degree of engineering while continuing in service as sub Engineers shall be eligible for promotion to the post of Assistant Engineer in 8 years of service and quota of 10 per cent posts has been earmarked for such category. If we accept the contention of Mr. Ashok sen	 it would defeat the very scheme and the purpose of giving incentive of adding educational qualification by diploma holders while continuing in service in case the period of 8 years ' is counted from the date of obtaining graduate degree in engineering. It may be noted that no such argument was raised even from the side of the respondents before the Tribunal. If such interpretation as now sought to be advanced by Mr. Ashok Sen	 learned senior counsel is accepted	 no relief could have been granted to the respondent Satish Kumar Pandey. We would illustrate the above position on admitted facts that Shri Satish Kumar Pandey had joined as Sub Engineer on 23.8.1980	 but had acquired the degree of engineering in May	 1987. In that situation	 Mr. Satish Kumar becomes eligible only in May 1995 and he could not be considered as eligible in December 1989 when these Sub Engineers were considered for promotion as Assistant Engineers. Even othrwise	 if this period of 8 years is counted from the date of acquiring degree then this incentive of adding the qualification during the continuation of service and getting the advantage of acceleration in promotion in 8 years would for all practical purposes become nugatory and of no benefit. It is further important to note that in the cases before us	 the Government itself has been adopting the practice and making promotion as contended by the appellants and we are upholding such practice. In N. Suresh Nathan 's case also this Court had upheld the practice followed by the Government. It is also well settled principle of service jurisprudence that in the absence of any specific rule	 the seniority amongst persons holding similar posts in the same cadre has to be determined on the basis of the length of service and not on any other fortuitous circumstance. Though	 in the cases of special leave petitions filed by Shri Ram Sharan Gupta & Others vs The State of M.P. & Others and Shri N.N. Asthana & Another vs Shri Harish Kumar Ahuja & Others	 the parties belonged to the Irrigation Department of the State of Madhya Pradesh and were governed with different set of rules	 but the controversy arising in these cases is amply covered with the view taken by us and determined in the manner indicated above. In these circumstances mentioned above	 we are clearly of the view. that the Tribunal was wrong in determining the seniority from the date of acquiring degree of engineering and it ought to have been determined on the basis of length of service on the post of Sub Engineer and the State the basis of length of service on the post of Sub Engineer and the State Government was right in doing so and there was no infirmity in the orders passed by the Government. In the result	 we allow these appeals	 set aside the orders of the Tribunal dated 15.10.1991	 28.11.1991 and 17.9.1991 and 8upheld the orders passed by the Government in all these cases. In the facts and circumstances of the case	 no order as to costs. Appeals allowed.

The appellants and the private respondents were Sub Engineers in Public Health Engineering Department of the Government. The minimum period for Sub Engineer to qualify for promotion to the post of Assistant Engineer was 12 years for diploma holders and 8 years for such Sub Engineers who obtained the degree of graduation in the course of service. By an executive order dated 7.2.1989	 quota of direct recruitment was reduced to 50 per cent and the quota by promotion from the Sub Engineers	 Draftsman	 increased to 50 per cent. The 50 per cent quota by promotion was sub divided. The promotion quota for category of the Graduate Sub Engineers completing 8 years of service was 10%. The principle of counting the seniority was from the date of their continuous officiation irrespective of the date on which such diploma holder Sub Engineer acquired degree of graduation in engineering. The Departmental Promotion Committee considered the cases of 30 Graduate Sub Engineers for promotion to the post of Assistant Engineers and by order dated 4.12.1989 it prepared a panel of 18 Graduate Sub Engineers found suitable for promotion to the post of Assistant Engineer. On 6.12.1989 the Government promoted one M.B.Joshi and six others as Assistant Engineer	 who are appellants in appeal arising out of Special Leave Petition No.2507 of 1992. The Private respondents in the appeal	 filed and application in the State Administrative Tribunal challenging the orders dated 4.12.1989 and 6.12.1989. They contended that the seniority for the purpose of promotion to the post of Assistant Engineers in 10 per cent quota of Graduate Sub Engineers completing 8 years of service ought to have been considered from the date of attaining the graduate degree of engineering and not from the date of attaining the graduate degree of engineering and not from the date of appointment as Sub Engineer. The Tribunal allowed the petition placing reliance on its earlier decision in Sanaulla Sunzani V. State of M.P. & Ors.	 T.A. No. 771/88. The Tribunal held that the applicants (private respondents in the appeal) having secured the degrees in engineering prior to respondents 3 to 9 ( the appellants in the appeal) would rank higher in the graduation list of Graduate Sub Engineers. It directed the State Government and Engineer in Chief	 Public Health Engineering Department to convene a special D.P.C. to consider the applicants for promotion to the post of Assistant Engineers as on 4.12.1989 and if found suitable for promotion	 promote them and give them seniority over respondents 3 to 9. Identical questions of law were involved in all the appeals (C.A. Nos. 4255 57 of 1992)	 which were preferred against the judgments of the Tribunals. The appellants contended that so far as the post of Sub Engineers was concerned	 the minimum qualification prescribed was diploma holder and the seniority was determined on the basis of the date of appointment on the post of Sub Engineer irrespective of the fact that the person joining such post was a degree holder or a diploma holder; that the scale of pay was similar and the diploma holder and degree holder Sub Engineers stood on the same footing and their gradation list was prepared on the basis of length of service in the cadre of Sub Engineers that in the service jurisprudence where the rules were silent	 the seniority was always determined on the basis of length of service amongst the employees appointed on a similar post in the same cadre; that obtaining a degree during the continuation of service as Sub Engineer simply accelerated the entitlement to promotion for the post of Assistant Engineer from 12 years to 8 years but it did not in any manner disturb the seniority which was already settled on the basis of length of service on the post of Sub Engineer; and that the D.P.C. rightly prepared the panel of selection and the Government took a correct decision in issuing the order dated 6.12.1989. 2 The respondents contended that it was necessary to obtain the degree of engineering for being qualified for promotion to the post of Assistant Engineer within a period of 8 years instead of 12 years; that the period of 8 years to be counted from the date when the diploma holder Sub Engineer acquired the degree of engineering and not prior to said date. Allowing the appeals	 this Court	 HELD: 1.1. It is a well settle principle of service jurisprudence that in the absence of any specific rule	 the seniority amongst persons holding similar posts in the same cadre has to be determined on the basis of the length of service and not on any other fortuitous circumstance.[12 B] 1.2. The Government itself has been adopting the practice and making promotion as contended by the appellants. Such practice is upheld by the Court. [12 A] 1.3. The Rules do not contemplate any equivalence of any period of service with the qualification of acquiring degree of graduation in engineering. The Rules clearly provide that the diploma holders having obtained a degree of engineering while continuing in service as Sub Engineer shall be eligible for promotion to the post of Assistant Engineer in 8 years of service and quota of 10 per cent posts has been earmarked for such category of persons. [11 C D] 1.4. If the period of 8 years is counted from the date of acquiring degree then this incentive of adding the qualification during the continuation of service and getting the advantage of acceleration in promotion in 8 years would for all practical purposes become nugatory and of no benefit. [11 G H] 1.5. The Tribunal was wrong in determining the seniority from the date of acquiring degree of engineering and it ought to have been determined on the basis of length of service on the post of Sub Engineer and the State Government was right in doing so and there was no infirmity in the orders passed by the Government. [12 D E] N. Suresh Nathan & Anr. vs Union of India & Ors.	 [1992] Supp.1 SCC 584	 explained.