Revocation of registration cancellation allows registered persons to apply for reinstatement; proper officer may revoke or reject after hearing. The Model GST provision allows a registered taxable person whose registration was cancelled on the proper officer's own motion to apply, in the prescribed manner and period, for revocation of the cancellation; the proper officer may revoke or reject the application for good and sufficient reasons, but must issue a notice to show cause and afford a reasonable opportunity of being heard; revocation under one GST Act is deemed to operate under the corresponding GST Act.