Approved superannuation fund winding up restricted unless employer's trade is wound up or discontinued under Income-tax Rules. An approved superannuation fund established under an irrevocable trust cannot be wound up except when necessitated by the winding up or discontinuance of the employer's trade or undertaking; Rules 93 and 94 of the Income-tax Rules are analogous to the rules for gratuity funds and rule 3(a) of Part B of the Fourth Schedule requires establishment in connection with a trade or undertaking.