S. 12AA: Procedure for registration-Trust or institution-Cancellation-Reference by Assessing Officer after conclusion of assessment proceedings-Reference to Principal Commissioner without jurisdiction-Cancellation of registration held invalid–Provision inserted with effect from 1-4-2022-Not applicable to earlier assessment years-Show-cause notices and cancellation order quashed-Direction that cancellation would survive irrespective of finding on specified violation-Colourable exercise of power-Order quashed. [S. 12AB(4), 127(2), 143(3)]