Assessee entering into agreement to purchase 100 Aircrafts from French manufacturer with option to select engine to be fitted therein.  Engine manufacturer giving assessee credit for selecting its engines. Credits not subsidy or  discount or  commission.  Assessee not engaged in trading of  Aircraft or  business of  receiving credits. Credits received in form of  money and not benefit or perquisite arising from business. Credits not incidental to or derived from business of  operation of  commercial Aircraft. Not a case of  adventure in nature of  trade. Subsequent acquisition of  Aircraft on  lease not material. Purpose of  credits to provide support for Aircraft acquisition. Credits were capital receipt. No sale consideration flowing to assessee from lessors assessable to Capital gains tax.   No presumption that transaction or agreement is colourable or  sham-Construction of document primarily to be on basis of  terms and conditions therein-Nature of  receipt to be judged in hands of  recipient.  Entries in books of  account not determinative of  character of  receipt as income. (AY.2012-13)