Held that  final assessment order passed by Assessing Officer did not bear any Document Identification Number (DIN) and revenue failed to bring on record any exceptional circumstances as mentioned in Circular No. 19/2019, dated 14-8-2019 which would sustain communication of final assessment order manually without DIN, assessment order was to be treated as never been issued Circular No. 19/2019 dated 14-8-2019 has mandated income tax authority with effect from 1-10-2019 for generation, allotment and communication of computer generated DIN in relation to any assessment, appeals, orders, statutory or otherwise, exemptions, enquiry, investigation, verification of information, penalty, prosecution, rectification, approval etc.. (AY. 2012-13)