S. 251 : Appeal-Commissioner (Appeals)-Powers-Inadvertently omitted to make claim for deduction under section 10B-All necessary facts were already on record-CIT (A or Appellate Tribunal ought to have entertained claim-Unlike an ordinary appeal, basic purpose of a tax appeal is to ascertain correct tax liability of assessee in accordance with law-Matter remanded. [S. 10B, 250, 254(1)]