JUDGMENT Arijit Pasayat, C.J. 1. The Judgment of the Court was delivered by Pasayat, C. J.- Accepting an application under S.256(1) of Income Tax Act, 1961 (in short 'the Act'), following questions have been referred to this Court for opinion by Income Tax Appellate Tribunal, Cochin Bench (in short 'Tribunal'): "1. Whether on the facts and in the circumstances of the case the Appellate Tribunal was right in holding that even though the assessee might be entitled to the claim for deduction under S.35B (1) (b) (viii) of the Income Tax Act the said claim cannot be entertained as the order of the Income Tax Officer sought to be rectified had merged with the order of the Appellate Tribunal? 2. Whether on the facts and in the circumstances of the case is not the assessee entitled to be allowed its claim for deduction under S.35 B(1) (b) (viii) of the Income Tax Act by rectification of the assessment order for the year 1980-81?" 2. Factual position, which is also undisputed, is as follows: Assessee is a company carrying on business as engineers and contractors. During the course of assessments for assessment year 1980-81, assessee had claimed deductions under S.35B (1)(b) (iv) and (vii) of the Act. Assessing officer, by notice dated 18th July 1993, required assessee to show cause as to why said claims shall not be disallowed. Assessee filed detailed objections on 21st July 1983, but in assessment order dated 14th September 1983, there was no reference to the claim for deduction. Being aggrieved by said order of assessing officer, an appeal was preferred before Commissioner of Income Tax (Appeals) [in short 'C.I.T. (A)'] on various grounds including denial of deductions as claimed. By order dated 8th October 1985, C.I.T. (A) rejected claim of assessee. Matter was further carried by assessee before Tribunal on various grounds including denial of deductions as claimed. By order dated 12th May 1,987 in LT.A. Nos. 835 to 835/Coch/ 1985 relating to four assessment years including 1980-81, deductions as claimed were allowed. By order dated 8th October 1985, C.I.T. (A) rejected claim of assessee. Matter was further carried by assessee before Tribunal on various grounds including denial of deductions as claimed. By order dated 12th May 1,987 in LT.A. Nos. 835 to 835/Coch/ 1985 relating to four assessment years including 1980-81, deductions as claimed were allowed. While the above mentioned appeals were pending before Tribunal, assessee made a claim by a petition filed on 19th November 1986 before assessing officer for rectification of assessment order for the year in question under S.154 of the Act and to allow claim under S.35B (1) (b] (viii) in respect of expenditure incurred wholly and exclusively for performance of services in connection with execution or contracts for supply of service and facilities at Bhutan. Total expenditure was stated to be Rs. 34,22,367.18 and eligible deduction (one third thereof was Rs. 11,40,189. Assessing officer rejected the petition by order dated 23rd January 1989. Appeal was preferred before C.I.T. (A) against order rejecting application for rectification under S.154. Assessee's stand was that when materials were available in assessment record for grant of relief, application under S.154 was clearly maintainable and relief could not be refused merely on the ground that assessee had omitted to claim same originally. C.I.T. (A) dismissed appeal by its order dated 17th May 1990. Assessee preferred an appeal before Tribunal. By order dated 11th August 1995, appeal was dismissed on the ground that order of assessing officer had already merged with the order of appellate authority and, therefore, claim raised could not be entertained. Assessee, in its application under S.256 (1) of the Act, pointed out that application was made much before the order of Tribunal, but assessing officer had not disposed of the same expeditiously. In any event, issue was not before Tribunal in connected appeals. Therefore, assessment order could not have merged with appellate order. As indicated above, Tribunal accepted the prayer for reference and referred questions, as set out above, for opinion. 3. Learned counsel for assessee submitted "that authorities failed to consider the true scope and ambit of S.154 of the Act in its proper perspective. Since all relevant materials were on record, claim should have been allowed. According to him, when any mistake apparent from record is noticed, jurisdiction is conferred on assessing officer for rectifying the mistake. 3. Learned counsel for assessee submitted "that authorities failed to consider the true scope and ambit of S.154 of the Act in its proper perspective. Since all relevant materials were on record, claim should have been allowed. According to him, when any mistake apparent from record is noticed, jurisdiction is conferred on assessing officer for rectifying the mistake. Expression "record" as used in S.154 will include all materials which, form part of assessing proceedings and not only the return. Even if there was omission to claim relief allowable to him, it could not be said that he is not entitled to get relief. Learned counsel for Revenue, on the other hand, submitted that in view of definite limits of jurisdiction exercisable under S.154, prayer has not been rightly entertained. 4. Though question of merger of assessment order with the appellate order was noticed by Tribunal, learned counsel for parties submitted that said question is really of academic interest, when applicability of S.154 of the Act is decided. 5. S.154 deals with rectification of mistakes. Said provision, at the relevant time, so far relevant, reads as follows: "154. Rectification of mistake. (1) With a view to rectifying any mistake apparent from the record (a) the Income Tax Officer may amend any order of assessment or of refund or any other order passed by him; (b) the Appellate Assistant commissioner or the Commissioner (Appeals) may amend any order passed by him under S.250 orS.271; (e) the Commissioner may amend any order passed by him in revision under S.263 or S.264. * * * (2) Subject to the other provisions of this section, the authority concerned -- (a) may make an amendment under sub-S.(1) of its own motion, and (b) shall make such amendment for rectifying any such mistake which has been brought to its notice by the assessee, and where the authority concerned is the Appellate Assistant Commissioner or the Commissioner (Appeals) by the Income Tax Officer also. * * * In order to bring an application under S.154, the mistake must be "apparent" from record. "Apparent" means 'open to view, visible, evident, appears, appearing as real and true, conspicuous, manifest, obvious, seeming'. S.154 does not enable aa order to be reversed by revision or by review, but permits only some error which is apparent on the face of record to be corrected. "Apparent" means 'open to view, visible, evident, appears, appearing as real and true, conspicuous, manifest, obvious, seeming'. S.154 does not enable aa order to be reversed by revision or by review, but permits only some error which is apparent on the face of record to be corrected. Where an error is far from self evident, it ceases to be an apparent error. It is, no doubt, true that a mistake capable of being rectified under S.154 is not confined to clerical or arithmetical mistakes. On the other hand, it does not cover any mistake which may be discovered by a complicated process of investigation, argument or proof. As observed by apex Court in Master Construction Co. (P) Ltd. v. State of Orissa (1966) 17 S.T.C. 364 an error which is apparent on the face of record should be one which is not an error which depends for its discovery on elaborate arguments on questions of fact or law. Similar view was also expressed in Satyanarayan Laxminarayan Hegde v. Mallikarjun Bhavanappa Tirumale AIR 1960 SC 137 , It is to be noted that the language used in Order XLVII, R.1 of Code of Civil Procedure, 1908 (in short 'C.P.C.') is different from the language used in S.154 of the Act. Power is given to various authorities to rectify any mistake "apparent from record" under S.154 of the Act. In C.P.C., the words are "an error apparent on the face of the record". The two provisions do not mean the same thing. Power of officers mentioned in S.154 to rectify "any mistake apparent from the record" is undoubtedly not more than that of the High Court to entertain a writ petition on the face of "an error apparent on the face of the record". [see: T. S. Balaram, I.T.O. v. Volkart Bros (1971) 82 I.T.R. 50 (S.C.). Mistake is an ordinary word, but in Taxation Laws, it has a special significance. It is not an arithmetical or clerical error alone that comes within its purview. It comprehends errors which, after a judicious probe into the record from which it is supposed to emanate, are discerned. The word 'mistake' is inherently indefinite in scope, as what may be a mistake for one may not be one for another. It is mostly subjective and the dividing; line in border areas is thin and indiscernible. It comprehends errors which, after a judicious probe into the record from which it is supposed to emanate, are discerned. The word 'mistake' is inherently indefinite in scope, as what may be a mistake for one may not be one for another. It is mostly subjective and the dividing; line in border areas is thin and indiscernible. It is something which a duly and judiciously instructed mind can find out from the record. In order to attract the power to rectify under S.154, it is not sufficient if there is merely a mistake in the orders sought to be rectified. The mistake to be rectified must be one apparent from the record. A decision on a debatable point of law is not a mistake apparent from the record. The plain meaning of the word "apparent" is that it must be something which appears to be so ex facie and it is incapable of argument or debate. It, therefore, follows that a decision on a debatable point of law or fact or failure to apply the law to a set of facts which remains to be investigated cannot be corrected by way of rectification. As was observed in Anchor Pressings (P] Ltd. v. C.I.T. (1986) 161 I.T.R 159 jurisdiction under S.154 to rectify mistake is no doubt wider than that provided in order XLVII, rule I, C.P.C. Nonetheless, there must be material to support claim for a particular relief and unless such material can be referred to, no grievance can be made if assessing officer refuses such relief. 6. In view of the legal position as set out above, the authorities were justified in not accepting claim of assessee for rectification under S.154 of the Act. 7. Question No. 2 referred to above is answered against assessee and in favour of Revenue. In view of said answer, other question is really of academic nature and is not answered. Reference Application is accordingly disposed of.