ORDER : A. Rajasheker Reddy, J. 1. This writ petition is filed against the order dated 30-05-2016 passed in OA No.021/00986/2015 by the Central Administrative Tribunal, Hyderabad Bench whereby and whereunder the OA filed by the writ petitioners seeking to include their names in the select list for being considered for promotion from State Forest Service to Indian Forest Service (IFS) for the panel year 2013 under Indian Forest Service (Appointment by Promotion) Regulations, 1966 (for short, “the IFS Regulations 1966”) was dismissed. 2. In nutshell, the case of the petitioners is as follows:- The petitioners joined State public service as Forest Range Officers in the year 1980 having been selected through competitive examination conducted by the A.P. Public Service Commission. On representations made by the petitioners, in the year 2004, the 6th respondent-Principal Chief Conservator of Forests addressed letter to the State Government to accord permission to appoint the Forest Range Officers, which include the petitioners herein, as Assistant Conservator of Forests (ACFs) on ad-hoc basis. The State Government, in response thereto and upon consideration of the matter, issued GO Ms.No.12, dated 12-02-2004, accorded permission, subject to condition that promotees will not be entitled to any right to be placed on probation against vacancies meant for direct recruit ACFs, as they were being promoted in the vacancies meant for the direct recruitees ACFs. By order dated 14-06-2004 passed by the 6th respondent-Principal Chief Conservator of Forests, the petitioners were appointed as Assistant Conservator of Forests by imposing the condition as stipulated in GOMs.No. 12, dated 12-02-2004. The petitioners having been promoted and appointed as ACFs in the year 2004, completed 8 years of service by 2012 in the category of ACFs on ad-hoc basis. 3. The following is the data as to the date appointment of the petitioners as Forest Range Officers, their promotion to the post of Assistant Conservator of Forests on ad-hoc basis, their appointment in the substantive vacancies under promotion quota as ACFs and date of appointment as full member in the post of ACFs:- Sl. 3. The following is the data as to the date appointment of the petitioners as Forest Range Officers, their promotion to the post of Assistant Conservator of Forests on ad-hoc basis, their appointment in the substantive vacancies under promotion quota as ACFs and date of appointment as full member in the post of ACFs:- Sl. No. Name & Date of Birth Date of appointment as Forest Range Officer (FRO) Date of promotion as ACF on ad- hoc basis against DR vacancy Date of adjustment in the substantive vacancy under promotee quota/ commencement of probation Date of completion of probation as ACFs Date of Appointment of Full Member as ACFs 1 Y.Ramesh (20-05-1959) 14-03-1980 08-09-2004 30-08-2012 29-08-2013 30-08-2012 2. C.Venugopala Rao (20-06-1960) 14-11-1980 21-06-2004 01-10-2012 30-09-2013 01-10-2012 3. K.Shailendra Moses (02-01-1959) 14-11-1980 15-07-2004 01-11-2012 31-10-2013 01-11-2012 4. S.Narender Reddy (05-02-1960) 14-11-1980 09-07-2004 01-11-2012 31-10-2013 01-11-2012 Through the State Forest Services Association, the petitioners made representations to consider their cases for further promotion/appointment to Indian Forest Service (IFS) under the Regulations 1966 and include their names in the select list of the panel year 2013. 4. The eligibility criteria governing appointment by promotion of State Forest Service officers to Indian Forest Service is enunciated in Rule 5 (2) of the Regulations 1966 which mandates, among other things, that the officer of State Forest Service has to complete not less than eight years of continuous service (whether officiating or substantive) in posts included in the State Forest Service. The case of the petitioners could not be considered and their names did not find place in the select list of the panel year 2013 purportedly on the ground that the ad-hoc service rendered by them against direct recruitee posts of Assistant Conservator of Forests could not be counted as service rendered in substantive posts of promotion quota and their officiating service on ad-hoc basis was not sufficient to meet the statutory requirement of eight years substantive service in the State Forest Service. Feeling aggrieved by such rejection of their candidatures for appointment by promotion to IFS, petitioners filed the above OA and by the impugned order, the OA was dismissed. Hence, this writ petition. 5. Feeling aggrieved by such rejection of their candidatures for appointment by promotion to IFS, petitioners filed the above OA and by the impugned order, the OA was dismissed. Hence, this writ petition. 5. Counter affidavit is filed by the Principal Chief Conservator of Forests- 5th respondent on his behalf, as also on behalf of respondents 1 and 3 wherein inter-alia it is stated that the ad-hoc service rendered by the petitioners from the date of their ad-hoc appointment as ACFs against the vacancies meant for direct recruitment quota, their service in the said posts shall be reckoned only from the date on which they occupy the vacancies meant for them (promotee quota). That the claim of the petitioners to consider the service rendered as Forest Range Officers including the service as ACFs (both ad-hoc and regular service) for computing the qualifying service for promotion to IFS cadre is too remote proposition as service rendered as Forest Range Officer is not a qualifying service for promotion to IFS cadre and nowhere in the AP Forest Service Rules it is provided that such a service is a feeder category and the service rendered in that category is countable for IFS promotions. That till date, whatever select lists are prepared, accepted by the Ministry of Environment and Forest/Department of Personnel and Training/Union Public Service Commission and given promotions to Indian Forest Service cadre are based on seniority list of State Forest Service Officers consisting of ACFs and Dy. Conservators of Forests only. 6. Respondents 2, 4 and 6 filed counter affidavit on similar lines of the counter affidavit filed by the respondents 1* 3 & 5. It is stated that direct recruit ACFs becomes full member of the cadre from the date of their appointment and since their appointment is against the substantive vacancy under direct recruitment quota whereas, a promotee ACF will become full member from the date of his actual promotion under the substantive vacancy under promotee quota. All the promotees including the petitioners have accepted the terms and conditions of promotion and joined the post of ACFs on ad-hoc basis. The petitioners were put on probation in the substantive post of ACFs in the year 2012 and their service in the feeder category for promotion to IFS would be counted from the year 2012. All the promotees including the petitioners have accepted the terms and conditions of promotion and joined the post of ACFs on ad-hoc basis. The petitioners were put on probation in the substantive post of ACFs in the year 2012 and their service in the feeder category for promotion to IFS would be counted from the year 2012. That Government of India issued clarification for counting eight years of continuous service (officiating or substantive) vide Memo No.22012/50/2000-IFS-II, Ministry of Environment and Forests, dated 22-10-2001 and Circular Memo No.16/Ser.A/93-39 GA (Ser.A) Department, dated 21-04-1999 wherein it was clarified that if any employee is promoted to a post earmarked for direct recruitment, his probation shall not commence from the date of his appointment into the slot earmarked for direct recruitment, but shall be reckoned only from the date on which he would have occupied the vacancy meant for promotees. As per the clarifications/guidelines issued by Government of India, the period of ad-hoc service of the petitioners is not countable to compute eight years of substantive service since the petitioners have not completed eight years of continuous service as full members under the category of ACFs, hence their names were not included in the select list of the panel year 2013 for appointment by promotion to Indian Forest Service (IFS). 7. Rejoinder is filed by the 1st petitioner on his behalf as also on behalf of the other petitioners. It is stated that the petitioners who were promoted as ACFs in the year 2004 have completed 8 years of service by September, 2012 in the post of ACFs and thus there are eligible for consideration and inclusion of their names in the select of list for promotion to IFS. That under Regulation 5(2) of the Regulations, 1966, substantive service includes service in officiating capacity and it is sufficient that the petitioners have performed the duties of the qualifying post. 8. That under Regulation 5(2) of the Regulations, 1966, substantive service includes service in officiating capacity and it is sufficient that the petitioners have performed the duties of the qualifying post. 8. 7th respondent-Union of India represented by its Secretary, Ministry of Environment & Forest filed counter affidavit wherein inter-alia it is stated that the exercise to finalize the eligible candidates and to recommend their names including the petitioners, subject to their eligibility, for promotion from State Forest Service to Indian Forest Service (IFS) is the function of the State as the service records of the candidates are maintained by it and to consider the eligibility or otherwise of the candidates to be included in the select list for forwarding the same to the UPSC for promotion to IFS is within the realm of the State and the eligibility of the candidates to be included in the select list has to be worked out by the State Government. 9. Counter affidavits are filed by the impleaded party respondents 10 to 24 by way of vacate petitions. It is their case that the appointment of the petitioners by way of promotion to the post ACFs was purely on temporary and on ad-hoc basis without right of probation in the said post and they are liable to be reverted to the cadre of Forest Range Officer as and when direct recruitees occupy such posts meant for them. That fortuitous service rendered in a vacancy outside the quota would not confer any right much less seniority. In order to count the service for any purpose even officiating service, such appointment made should be in accordance with the Rules, inasmuch as the very appointment of the petitioners by promotion as ACFs is against direct recruit vacancies, no rights flow from such appointment. That the petitioners have given undertaking that their appointment was purely an interim and ad-hoc basis and they will not make any legal claims in case of their reversion to the lower cadre. That the petitioners having accepted conditional ad-hoc promotions against direct recruit vacancies, cannot turn around and contend that the said service shall be treated as officiating service against substantive vacancy and they cannot be permitted to approbate and reprobate. That the petitioners having accepted conditional ad-hoc promotions against direct recruit vacancies, cannot turn around and contend that the said service shall be treated as officiating service against substantive vacancy and they cannot be permitted to approbate and reprobate. That 6 vacancies in 2013, 1 vacancy in 2014, 3 vacancies in 2015, 1 vacancy in 2016, 2 vacancies in 2017 and 5 vacancies in 2018 arose and these vacancies exist for appointment by promotion from State Forest Service to Indian Forest Service (IFS), but due to the order of status- quo, the selection process could not be undertaken from 2013 onwards and the promotions of the party respondents are stalled. That almost all the petitioners have retired from service by this time. The other averments are similar averments which are already noted above hence need not be repeated. 10. Heard Sri D. Prakash Reddy, learned senior counsel for Sri Avinash Desai, learned counsel for the petitioners, learned Addl. Advocate General for Government Pleader for Services (TS) for respondents 1, 3 & 5, Sri Govind Reddy Panati learned Counsel appearing for respondents 2, 4 & 6, Sri Namavarapu Rajeshwar Rao, learned Assistant Solicitor General of India for respondent 7, learned Standing Counsel for respondent no.8, Sri P.Suresh Reddy, learned senior counsel for Sri Nagam Chandrasekhar Reddy, learned counsel for respondents 10 to 15, Sri V. Ravichandranlf learned counsel for respondents 16 to 23, Sri G. Vidya Sagar, learned senior counsel for Sri J. Srinivasa Rao, learned counsel for respondent no.24 & Sri MV Rama Rao, learned counsel for respondents 24 to 29. 11. The contentions of Sri D. Prakash Reddy, learned senior counsel appearing for the petitioners can be summarized as under:- That the petitioners are eligible for being considered for promotion under Rule 5 (2) of the IFS Regulations 1966 having completed eight years of officiating service in the cadre of ACFs as the Rule provide of consideration continuous service whether officiating or substantive. That the continuous service rendered by the petitioners is to be considered as “officiating” service as any contrary interpretation would otiose the use of the word “officiating” in Rule 5 (2) of the IFS Regulations 1966. That the continuous service rendered by the petitioners is to be considered as “officiating” service as any contrary interpretation would otiose the use of the word “officiating” in Rule 5 (2) of the IFS Regulations 1966. That Rule 8 (b) of the Andhra Pradesh Forest Service Rules, 1977 (for short, “the Forest Service Rules”) requires promotee shall be on probation for a period of one year is a State service requirement, but there is no such mention in the IFS Regulations 1966 for appointment by promotion to IFS and such a requirement is applicable to promotions within the State Forest Service. That Rule 2 (18) of the State and Subordinate Service Rules defines a ‘member of service’ as a person who has been appointed to that service and specifically includes a probationer and the rule itself recognize the petitioners as full members of service and no need to be placed on probation for promotion to IFS. That under Rule 21 (a) of the State and Subordinate Service Rules a person appointed initially in a service and is declared or deemed to have satisfactorily completed his probation, he will be confirmed as a member of that service by the appointing authority and under Explanation (3) thereto, a person appointed to a Government service and confirmed in service only once during his service at the entry grade, irrespective of whether subsequently he is promoted within the same service or appointment by transfer to some other service and therefore there was no requirement for the petitioners to be confirmed full members of service as ACFs. 12. The contentions of Sri G.Vidya Sagar, Sri P. Suresh Reddy, learned senior counsel, Sri V. Ravichandran, Sri J. Srinivasa Rao, & Sri MV Rama Rao, learned counsel representing the party respondents can be summarized as under:- (a) That ad-hoc service rendered by the petitioners cannot be counted as officiating service unless expressly provided for in the relevant Recruitment Rules or the Regulations 1966. (b) That petitioners were promoted and placed on probation in the posts of ACFs in August/November 2012 and not in substantive posts of ACFs on 01-01-2013, they were not entitled to be considered for promotion and inclusion of their names in the select list of 2013. (b) That petitioners were promoted and placed on probation in the posts of ACFs in August/November 2012 and not in substantive posts of ACFs on 01-01-2013, they were not entitled to be considered for promotion and inclusion of their names in the select list of 2013. (c) That the eligibility for promotion of a member of State cadre is specified in Rule 8 of the State and Subordinate Service Rules and it is incumbent upon a member of service to satisfactorily complete his probation in the cadre from which he is proposed to be promoted. (d) That petitioners promoted on ad-hoc basis as ACFs themselves gave an undertaking that they would not claim any right to be placed on probation, as such the ad-hoc service without being placed on probation and the approval from the Public Sendee Commission cannot be counted as officiating service. That the relief sought by the petitioners amounts to seeking retrospective promotion and seniority from the date on which there was no vacancy for promotees. (e) That under Rule 20(5) of the State and Subordinate Service Rules a person is said to be officiating in a post if his appointment is made after his inclusion in the relevant panel and as the petitioners were appointed in the posts meant for direct recruitees and on ad-hoc basis they were not included in the select panel of the relevant year. 13. Learned Government Pleader for Services for the State of Telangana and the learned Special Counsel for the respondent-authorities of both the States submitted that the service rendered by the petitioners on ad-hoc basis as ACFs cannot be considered for the purposes of qualifying service of 8 years for promotions to IFS. They also submitted that the petitioners having given undertakings not to claim any seniority in that cadre now cannot be permitted to claim such a service as officiating service more so their names were not included in the select panel list. They have also drawn our attention to GO Ms.No.12, dated 12-02-2004 whereunder permission was granted to the Principal Chief Conservator of Forest to convene screening Committee meeting for considering the candidature of the petitioners for promotion as ACFs on temporary and ad-hoc basis. 14. They have also drawn our attention to GO Ms.No.12, dated 12-02-2004 whereunder permission was granted to the Principal Chief Conservator of Forest to convene screening Committee meeting for considering the candidature of the petitioners for promotion as ACFs on temporary and ad-hoc basis. 14. This case raises a piqued question of service jurisprudence, viz., whether the petitioners who were temporarily promoted on ad-hoc basis as Assistant Conservator of Forests in the vacancies meant for direct recruitees in the year 2004; continued as such till 2012; without being placed on probation in promotional post, whether such a service can be counted as officiating service, prior to their appointment in the substantive vacancy under promotee quota in the year 2012. The much hyped term is “officiating” and it is canvassed that the ad-hoc service rendered by the petitioners comes within the meaning of the term “officiating”. 15. Before we dwell into the legal aspects of this issue, it is necessary to note certain definitions and provisions of the Rules operating the field. The State Forest Service (now TS Forest Service & AP Forest Service) are governed by two sets of rules. The General Rules as contained in A.P. State and Subordinate Service Rules, 1996, adopted by the State of Telangana, are applicable to both the States Forest Services. The second set of rules are Special Rules viz., the Andhra Pradesh Forest Service Rules, 1997, adopted by the State of Telangana, applicable to State Forest Services posts in the State cadre. The Central Rules applicable for appointment to Indian Forest Service (IFS) are Indian Forest Service (Recruitment) Rules, 1966 (for short, the IFS (Recruitment) Rules and the IFS Regulations 1966 framed under sub-Rule (1) of Rule 8 of the IFS (Recruitment) Rules. It is noticed that even in the general Rule, Rule 4 (a) of the State and Subordinate Service Rules provide for enforceability of the Special Rules where the Special Rules provide for the methods of recruitment to the specified posts. It is settled proposition of law that general Rules provide broadly for recruitment to services of all the departments to cover situations that are not covered by the Special Rules of any particular department. In a given case where there are no Special Rules, then general Rules would be applicable. It is settled proposition of law that general Rules provide broadly for recruitment to services of all the departments to cover situations that are not covered by the Special Rules of any particular department. In a given case where there are no Special Rules, then general Rules would be applicable. In this case there is no patent conflict or inconsistency between the general and the Special Rules and both have to be harmoniously read J understood and applied. 16. The triple qualifying criteria for being eligible for consideration for promotion to the Indian Forest Service (IFS) from the State Forest service are viz., (i) the candidate must be substantive in the State Forest Service as on 1st January of the panel year; (ii) must have completed 8 years of continuous service (whether officiating or substantive) in posts included in the State Forest service; & (iii) must not have attained the age of 54 years as on 1st January of the year, in this case the relevant year is 2013. 17. Rule 4 of the IFS (Recruitment) Rules defines method of recruitment to the Indian Forest Service (IFS), reads as follows:- “4. Method of recruitment to the service:- (1) Omitted (2) Recruitment to the service shall be by the following methods, namely (a) by a competitive examination (b) by promotion of substantive members of the State Forest Service”. (underlined) 18. Rule 8 thereof defines method of recruitment by promotion, reads as follows:- “8. Recruitment by promotion:- 8 (1) The Central Government may, on the recommendations of the State Government concerned and m consultation with the Commission and in accordance with such regulations as the Central Government may, after consultation with the State Governments and the Commission, from time to time, make, recruit to the Service, persons by promotion from amongst the substantive members of the State Forest Service.” (underlined) 19. Eligibility criteria for appointment by promotion to IFS is prescribed in the IFS Regulations 1966 framed under sub-Rule (1) of Rule 8 of the IFS (Recruitment) Rules. Regulation 5 (1), (2) & (3) of the IFS Regulations 1966 reads as follows:- “5. Preparation of a list of suitable officers-5(1) Each Committee shall ordinarily meet every year and prepare a list of such members of the State Forest Service as are held by them to be suitable for promotion to the Service. Regulation 5 (1), (2) & (3) of the IFS Regulations 1966 reads as follows:- “5. Preparation of a list of suitable officers-5(1) Each Committee shall ordinarily meet every year and prepare a list of such members of the State Forest Service as are held by them to be suitable for promotion to the Service. The number of members of the State Forest Service to be included in the list shall be determined by the Central Government in consultation with the State government concerned, and shall not exceed the number of substantive vacancies as on the first day of January of the year in which the meeting is held, in the posts available for them under rule 9 of the Recruitment Rules. The date and venue of the meeting of the Committee to make the selection shall be determined by the Commission: [Provided that no meeting of the Committee shall be held, and no list for the year in question shall be prepared when; there are no substantive vacancies as on the first day of January of the year in the posts available for the members of the state Forest Service under rule 9 of the recruitment rules; or the Central Government in consultation with the State Government decides that no recruitment shall be made during the year to the substantive vacancies as on the first day of January of the year in the posts available for the members of the State Forest Service under rule 9 of the Recruitment Rules; Provided further that where no meeting of the Committee could be held during a year for any reason other than that provided for in the first proviso, as and when the Committee meets again, the Select List shall be prepared separately for each year during which the Committee could not meet, as on the 31st December of each year. EXPLANATION:- In case of Joint Cadres, a separate select list shall be prepared in respect of each State Forest Service. “5(2). The Committee shall consider for inclusion to the said list, the cases of members of the State Forest Services in the order of seniority in that service of a number which is equal to three times the number referred in sub-regulation (1). “5(2). The Committee shall consider for inclusion to the said list, the cases of members of the State Forest Services in the order of seniority in that service of a number which is equal to three times the number referred in sub-regulation (1). Provided that such restriction shall not apply in respect of a State where the total number of eligible officers is less than three times the maximum permissible size of the Select List and in such a case the Committee shall consider all the eligible officers. Provided further that in computing the number for inclusion in the field of consideration, the number of officers referred to in sub-regulation (3) shall be excluded; Provided also that the Committee shall not consider the case of a member of the State Forest Service unless on the first day of January of the year for which the Select List is prepared,, he is substantive in the State Forest Service and has completed not less than eight years of continuous service (whether officiating or substantive) in post(s) included in the State Forest Service, (emphasis supplied) EXPLANATION I...,, Provided Provided..., EXPLANATION II. EXPLANATION III. Provided” “5(3). The Committee shall not consider the case of the members of the State Forest Service who have attained the age of 54 years on the first clay of January of the year for which the Select List is prepared: (emphasis supplied) Provided.... Provided....” 20. The core point for consideration is whether the petitioners are in substantive in the State Forest Service for being eligible for consideration for promotion to the posts of IFS as on the date of relevant year i.e. 01-01-2013. Two terms assume greater importance in this case viz., officiating and substantive as appearing in 3rd proviso to Rule 5 (2) of the IFS Regulations 1966. It is to be seen that the words “substantive or officiating” are not defined either under the Special Rules of IFS (Recruitment) Rules or the IFS Regulations 1966 nor it has been pointed out that any definition that has been made is applicable. 21. The cardinal rule of construction of statutes is to read the statutes literally, that is, by giving to the words their ordinary, natural and grammatical meaning. If, however, such a reading leads to absurdity and the words are susceptible of another meaning, the Court may adopt the same. 21. The cardinal rule of construction of statutes is to read the statutes literally, that is, by giving to the words their ordinary, natural and grammatical meaning. If, however, such a reading leads to absurdity and the words are susceptible of another meaning, the Court may adopt the same. But if no such alternative construction is possible, the Court must adopt the ordinary rule of literal interpretation. (see RAM RATTAN vs. PARMA NAND). ( AIR 1946 PC 51 ). 22. The principles of rules of interpretation requires that the intention of the Legislature must be found in the words used by the Legislature itself. Since, Rules are legislative in character, their interpretation must be consistent with the intention of the Legislature. When words are clear and unambiguous and capable of one construction only, it is not open to adopt any other hypothetical construction. Words used must be interpreted in their plain and grammatical meaning. 23. Maxwell in his work, Interpretation of Statutes, Sixth Edition 1920, p 94 states: "In a word then it is to be taken as a fundamental principle, standing as it were on the threshold of the whole subject of interpretation, that the plain intention of the Legislature, as expressed by the language employed, is invariably to be accepted and carried into effect, whatever may be the opinion of the judicial interpreter of its wisdom or justice. If the language admits of no doubt or secondary meaning it is to be obeyed." 24. The dictionary meaning of the word “substantive” as defined in the Cambridge dictionary means, important, serious, or related to real facts. Merriam Webster dictionary defines as having substance: involving matters of major or practical importance to all concerned. Collins dictionary defines the terms as, existing independently; not dependent upon or subordinate to another. 25. In SATHBEDBVI vs. PRASANNA, 2010 (5) SCC 622 at paras 12 & 13, the Supreme Court observed as follows:- "The words used in the material provisions of the statute must be interpreted in their plain grammatical meaning and it is only when such words are capable of two Constructions that the question of giving effect to the policy or object of the Act can legitimately arise. The Court cannot rewrite, recast or reframe the legislation because it has no power to do so. The Court cannot add words to a statute or read words which are not therein it. The Court cannot rewrite, recast or reframe the legislation because it has no power to do so. The Court cannot add words to a statute or read words which are not therein it. Even if there is a defect or an omission in the statute, the Court cannot correct the defect or supply the omission. ” 26. In O.S. SINGH vs. UNION OF INDIA, (1996) 5 SCC 37, the Hon’ble Supreme Court has had the occasion to discuss and differentiate the terms substantive appointment and officiating appointment. Paragraph 8 thereof reads as follows:- "In service jurisprudence a distinction is made between a "substantive appointment” and an "officiating appointment While substantive appointment confers on the person so appointed a substantive right to the post, an officiating appointment does not confer any such substantive right. The appointment on officiating basis is usually made when the incumbent substantively holding that post is on leave or when the permanent post is vacant and no substantive appointment has yet been made to that post. Such an officiating appointment comes to an end on the return of the incumbent substantively holding the post from leave in the former case or a substantive appointment being made to that permanent post in the latter case. An appointment on officiating basis, is, from the very nature of such employment, itself of a transitory character and, under the ordinary law of master and servant, is terminable at any time, (see: Parshotam Lai Dhingra v. Union of India ( AIR 1958 SC 36 )”. 27. In service jurisprudence a post could be temporary or it could be permanent or it could be created for a definite period to meet a definite contingency. If an incumbent is appointed after due process of selection either to a temporary post or a permanent post and such appointment, not being either stopgap or fortuitous, could be held to be on substantive basis. But if the post itself is created only for a limited period to meet a particular contingency and appointment thereto is made not through any process of selection but on a stopgap basis then such an appointment cannot be held to be on substantive basis. The expression “substantive basis” is used in the service jurisprudence in contradistinction with ad-hoc or purely stopgap or fortuitous. The expression “substantive basis” is used in the service jurisprudence in contradistinction with ad-hoc or purely stopgap or fortuitous. There exists difference between a substantive post as contradistinguished from temporary post and appointment of an incumbent to these posts could be made either on substantive basis or on ad hoc or stop-gap basis. (see Ramesh K. Sharma v. Rajasthan Civil Services, (2001) 1 SCC 637 ). 28. The Hon'ble Supreme Court in R.K. SAIN vs. UOI, 2000 (8) SCC 25 considering the scope and use of the terminology of officiating, stop gap, ad-hoc at paragraph 19 held as follows:- “The meaning to be assigned to these terms while interpreting provisions of a service rule will depend on the provisions of that rule and the context in and the purpose for which the expressions are used. The meaning of any of these terms in the context of computation of inter-se seniority of officers holding cadre post will depend on the facts and circumstances in which the appointment came to be made. For that purpose it will be necessary to look into the purpose for which the post was created and the nature of the appointment of the officer as stated in the appointment order. If the appointment order itself indicates that the post is created to meet a particular temporary contingency and for a period specified in the order, then "stop gap". If a post is created to meet a situation which has suddenly arisen on account of happening of some event of a temporary nature then the appointment of such a post can aptly be described as "fortuitous" in nature. If an appointment is made to meet the contingency arising on account of delay in completing the process of regular recruitment to the post due to any reason and it is not possible to leave the post vacant till then, and to meet this contingency an appointment is made then it can appropriately be called as a "Stop gap" arrangement and appointment in the post as "ad hoc" appointment. It is not possible to lay down any strait-jacket formula nor give an exhaustive list of circumstances and situation in which such an appointment (ad-hoc, fortuitous or stop gap) can be made. It is not possible to lay down any strait-jacket formula nor give an exhaustive list of circumstances and situation in which such an appointment (ad-hoc, fortuitous or stop gap) can be made. As such, this discussion is not intended to enumerate the circumstances or situations in which appointments of officers can be said to come within the scope of any of these terms”. 29. The petitioners were appointed by promotion as Assistant Conservator of Forests on ad-hoc basis in the year 2004 against vacancies meant to be filled-up by direct recruitees and with a condition imposed that they will not be entitled to any right to be placed on probation till they are adjusted against substantive vacancy under promotee quota as stipulated in GO Ms.No.12, dated 12-12-2004. The petitioners continued on ad-hoc basis till 2012 and adjusted in the substantive vacancies under promotee quota in 2012 on even dates as stated supra in the tabular form. No doubt the petitioners put up eight years of continuous service as ad-hoc/temporary ACFs, and were promoted and placed on probation in the posts of ACFs meant for them in August/November 2012 and they were only probationers as on 01-01-2013. As on the cut off date i.e 01-01-2013, the petitioners were not substantive members in the cadre of Assistant Conservator of Forests (Category-2 of Class-A) of the State forest service, though members of service as defined in Rule 2 (18) of the State and Subordinate Service Rules as their probation was not declared on the relevant date, but were on rolls as such on ad-hoc basis, being substantive members in the cadre of Forest Range Officers which post is included in (Category-3 of Class-A). Either the General Rules or the Special Rules provide for counting such temporary/ad-hoc service as officiating service rendered by the petitioners. Either the General Rules or the Special Rules provide for counting such temporary/ad-hoc service as officiating service rendered by the petitioners. The definition of “officiating appointment” in Rule 20 (5) of the State and Subordinate Service Rules, which reads thus, “Rule 2 (20) Officiating Appointment:- A person is said to be officiating in a post, if his appointment has been made after his inclusion in the relevant panel, but whose appointment has not been regularized,” relates to a person who is said to be officiating in a post, if his appointment has been made after his inclusion in the relevant panel, as in this case the names of the petitioners were not included in the panel of the relevant year, as their were not in substantive in the State Forest Service in the cadre of ACFs. 30. The word “officiating” has been defined in Rule 9 (19) of the A.P. Fundamental Rules, which reads thus, “(19). "officiate" A Government servant officiates in a post when he performs the duties of the post on which another person holds a lien. A local Government may, if it thinks fit, appoint a Government Servant to officiate in a vacant post on which no other Government Servant holds a lien," but the said definition as appearing in the A.P. Fundamental Rules would not be much relevance unless the ad-hoc/temporary service rendered by the petitioners is construed to be officiating within the meaning of the 3rd proviso to Rule 5 (2) of the Regulations 1966. 31. Member of service means and includes a probationer as specified in Rule 2 (18) of the State and Subordinate Service Rules, which reads thus, “Rule 2 (18) Member of a Service: “Member of a Service” means a person who has been appointed to that service and who has not retired or resigned, or who has not been removed or dismissed, or substantively transferred or reduced to another service, or who has not been discharged otherwise than for want of a vacancy. He may be a probationer, an approved probationer or confirmed member of that service (underlined),” and as on the relevant date i.e. 1-1-2013, the petitioners were probationers in the cadre of ACFs, but not completed the probation period under Rule 2 (25) of the State and Subordinate Service Rules, which reads thus, “Rule 2 (25) Probationer:- "Probationer” means a member in a service class or category who has not completed his probation.” The petitioners have not completed the probation in the posts of ACFs hence they may be members of service in the cadre of ACFs but not holding the posts in substantive capacity. 32. Rule 8 (1) of the IFS (Recruitment) Rules which permits promotions to the members amongst the substantive members of the State Forest Service, reads thus, “8. Recruitment by promotion:- (1) The Central Government may, on the recommendations of the State Government concerned and in consultation with the Commission and in accordance with such regulations as the Central Government may, after consultation with the State Governments and the Commission, from time to time, make, recruit to the Service, persons by promotion from amongst the substantive members of the State Forest Serviced” As on the relevant date i.e. 01-01-2013, the petitioners were not in substantive cadre of ACFs as required under Section 4 (2) (b) of the IFS (Recruitment) Rules, 1966 for being empanelled for promotion to the posts of IFS. The word “substantive” is used in more than one place in the relevant rules and regulations i.e. in Rule 4 (2) (b) & 8 of the IFS (Recruitment) Rules, and 3rd proviso to Regulation 5 (3) of the IFS Regulations 1966, which indicated that the words “member of a service” cannot be equated to the word “substantive”. If the rule making authority intended to include every member of service for being eligible for the purpose of promotion to the posts of IFS, then they simply could have used the words “member of service” instead of using the word “substantive”. 33. But a plain understanding of the term Ad-hoc post/promotion it is an arrangement created for the purpose of carrying on with the services of the post temporarily until a permanent incumbent arrived to that post. The purpose of officiating service is to carry out the task of that officiated post in the absence and on behalf of the designated person. But a plain understanding of the term Ad-hoc post/promotion it is an arrangement created for the purpose of carrying on with the services of the post temporarily until a permanent incumbent arrived to that post. The purpose of officiating service is to carry out the task of that officiated post in the absence and on behalf of the designated person. As far as an officiating appointment arrangement is concerned, it depends on the exigencies of the service and conditions and the rules for officiating appointment. No doubt the petitioners have put up eight years of continuous service as ad- hoc/ temporary AFCs and the petitioners were promoted and placed on probation in the posts of AFCs in August/November 2012, but they were on probation as on 01-01-2013. 34. Rule 4 (2) (b) of the IFS (Recruitment) Rules provides the method of recruitment to Indian Forest Services, one by a competitive examination and by promotion of substantive members of the State Forest Service. Under Rule 2 (Constitution) of the State Forest Service Rules, Forest Range Officers are included in State Forest Service, however, the posts included in the State Forest Service have to be approved under Rule 2 (g) of the IFS (Recruitment) Rules by the Central Government. Forest Range Officers is not a service as approved by the Central Government for the purpose of the Rules under the IFS (Recruitment) Rules or the IFS Regulations 1966 for appointment by promotion to IFS and as such the petitioners being substantive members in the cadre of Forest Range Officers and completed 8 years of service in that post is of no avail. 35. Rule 21 (a) of the State and Subordinate Service Rules stipulates that as soon as a person appointed initially in a service or class of a service, is declared to have satisfactorily completed his probation or deemed to have satisfactorily completed his probation, he shall be confirmed as a member of that service by the appointing authority and under explanation (3) a person appointed to a Government service shall be confirmed in any service, only once during his service in Government at the entry grade, irrespective of whether subsequently he is promoted within the same service or appointment by transfer to some other service or class of service, is a general rule. But the Special Rules for State Forest services, Rule 8 (b) requires every person appointed either by promotion or by transfer shall, from the date on which he commences probation be on probation for a total period of one (1) year on duty within a continuous period of two years. This Rule mandates the petitioners who were promoted in the promotion quota vacancies of ACFs, shall have to necessarily undergo probation for a period of one year within a continuous period of two years and their date of probation will be determined from the date of their promotion as ACFs and then alone will become substantive members of ACFs, their seniority will be reckoned from the date of their appointment by promotion to that posts under Rule 33 (a) of the State and Subordinate Service Rules. 36. Another aspect of the matter which weigh against the claim of the petitioners, for considering their service in the posts of ACFs as eligible service for being empanelled in the list for conferring IFS, is that the petitioners retained lien over their substantive post held as Forest Range Officers in the event of reversion at any time. Thus, the petitioners were fully aware that the promotion granted to them is not substantive in nature but is purely temporary and on ad-hoc basis. In acceptance of the same, the petitioners have also executed undertakings agreeing for reversion to the lower cadre post of Forest Range Officer, without claiming any right for being placed on probation, from which the petitioners are now trying to wriggle out by claiming that their legal right cannot be taken away, forgetting the fact that but for executing the undertaking agreeing for promotion to ACFs on temporary and on ad-hoc basis, the petitioners would have continued in their substantive post as Forest Range Officer, till the vacancies arose to be filled up by them in the regular course. 37. Under Rule 10 of the IFS (Recruitment) Rules framed by the Central Government, in exercise of the powers conferred under sub-Section (1) of Section 3 of the All India Services Act, 1951, power is conferred on the Central Government in the event if any question arises as to the interpretation of the Rules. Rule 10 of the IFS (Recruitment) Rules, reads as follows:- “10. Rule 10 of the IFS (Recruitment) Rules, reads as follows:- “10. Interpretation:- If any question arises as to the interpretation of these rules, the same shall be decided by the Central Government.” Though it is contended by learned senior counsel appearing for the petitioners that if at all the intention of the Legislature was to provide consideration only of the cases of those persons who render service in the substantive capacity, there was no necessity for use of the word “officiating” in the 3rd proviso to Rule 5 (2) of the Regulations 1966, such a proposition cannot be appreciated in the light of clarification issued by Central Government under Rule 10 of the IFS (Recruitment) Rules to a query raised by the Chief Secretary, Government of Andhra Pradesh, vide letter dated 2210-2001 in the following terms:- “To The Chief Secretary Government of Andhra Pradesh Hyderabad. Sub: IFS (Appointment by Promotion) Regulations-Eligibility criterion for promotion of State Forest Service Officers to the Indian Forest Service Relating to the service rendered in the grade of SFS-Clarification- Regarding Sir, Attention is invited to the third proviso to sub- regulation (2) of regulation-5 of the IFS (Appointment by Promotion) Regulations, 1966 in accordance with which the selection Committee constituted under regulation-3 shall not consider a case of the member of the State Forest Service unless on the first day of January of the year in which it meets, he is not substantive in the State Forest Service and has completed not less than 8 years of continuous service (whether officiating or substantive) in the post(s) included in the State Forest Service. 2. Clarifications have been sought as to the nature of continuous 8 nears of service required for becoming eligible for promotion to the Indian Forest Service under the Promotion Regulations. The matter has been examined. It is observed that the normal rules position prevailing in the matter of promotions in all the Central Government Departments as also the UPSC that ad-hoc service rendered in the feeder grade cannot be counted for the purpose of fulfillment of eligibility condition for being considered for promotion to the higher post equally holds in the matter of promotion of State Forest Service officers to the Indian Forest Service in terms of the IFS (Appointment by Promotion) Regulations, 1966. In other words, in the absence of express provisions to the contrary in the relevant rules and regulations, the legal position is that ad-hoc service in the feeder-grade cannot be counted for the purpose of completion of minimum eligibility service in such grade for being considered for promotion to Indian Forest service (IFS). 3. The eight years service in the State Forest Service required for being eligible for promotion to the Indian Forest Service should be continuous whether officiating or substantive. The other condition being that one should be substantive in the State Forest Service on the first day of January of the year in which the Selection Committee meets. 4. The State Governments are requested to keep the above position in view while sending proposals to the UPSC for preparation of the Select list. Yours faithfully, Sd/- (xxxxxxx) Under Secretary to the Govt, of India” 38. The above circular and memo issued by the Government of India in exercise of the power vested in it under Rule 10 IFS (Recruitment) Rules are not challenged by the petitioners and, therefore, those circulars are binding on them as they form part of the Rules Hence, de-horse the various theories of term “ad-hoc” service, the meaning and interpretation adopted by the Central Government prevails, and it is statutorily enabled to do so, unless it is otherwise held in an action in a Court of law. 39. Though interpretation placed by Central Government is not binding on this Court, but since it is conferred with rule making power under the All India Services Act, 1951, to carry out the purposes of the Act and while making rules it has reserved the right to interpret the same under Rule 10 of the IFS (Recruitment) Rules, the said interpretation by way of above clarification has to be accepted as it intended so while making rule and that interpretation is given by way of the above clarification. Moreso, the said clarification is issued under the self-same IFS Regulations 1966 as such the contention of the learned senior counsel appearing for petitioners that since rules provide for counting of officiating service for promotion to IFS, second limb of clarification applies cannot be accepted. 40. Moreso, the said clarification is issued under the self-same IFS Regulations 1966 as such the contention of the learned senior counsel appearing for petitioners that since rules provide for counting of officiating service for promotion to IFS, second limb of clarification applies cannot be accepted. 40. The petitioners were promoted in the year 2012 in the vacancies meant for them, therefore they cannot claim their service with effect from their ad- hoc appointment in vacancies meant for direct recruitees, more particularly in view of their undertaking given by them that they will not claim any benefits of such appointment on ad-hoc basis and even prepared to revert back to the previous cadre in the event of direct recruitee occupying the said posts. The Government GO, GOMs.No.12, dated 12-02-2004 which permitted their appointment as such specifically imposed a condition that they shall not be placed on probation in the post of ACFs. With all these drawbacks in store, the petitioners cannot succeed to claim that they be considered as eligible for being empanelled for appointment by promotion to the IFS in the light of their ad-hoc service as officiating service within meaning of Rule 5 (2) of the Regulations 1996 and there are substantive courts in State Forest service. Though the petitioners have not completed 55 years as on the relevant date and were eligible for promotion on this count, but were not in substantive in the State Forest Service in the cadre of ACFs and not completed eight years of continuous service as such their cases could not be considered for promotion to the posts of IFS. 41. On the above analysis of the case, we do not see any illegality or irregularity in the impugned order passed by the Administrative Tribunal at Hyderabad. The writ petition being devoid of merits it is accordingly dismissed. No order as to costs. Miscellaneous petitions pending, if any, shall stand closed.