Revocation window for cancelled GST registrations: limited opportunity subject to filing returns and payment of dues. The notification permits registered persons whose registration was cancelled under clause (b) or (c) of sub-section (2) of section 29 and who failed to apply within the section 30 period to apply for revocation up to the prescribed extended date, but only after furnishing returns due up to the effective date of cancellation and after payment of tax, interest, penalty and late fee; no further extension is available. The Explanation includes persons whose appeals were rejected for failure to adhere to the time limit.