47 CFR §61.136

A concurrence may be revoked by a revocation notice or cancelled by a new concurrence. A revocation notice or a new concurrence, if less broad in scope than the concurrence it cancels, must bear an effective date not less than 45 days after its receipt by the Commission. A revocation notice is not given a serial number, but must specify the number of the concurrence to be revoked and the name of the carrier in whose favor the concurrence was issued. It must be in the following format: