Clearing member registration: certificate required, with specified exemptions and filing through the clearing corporation within set timelines. Regulation 10A mandates a certificate of registration from the Board for persons acting as clearing members, while exempting registered stock brokers and limited purpose clearing corporation participants in the tri party repo segment from separate registration subject to clearing corporation approval; it defines 'participant' by reference to the Repo Directions. Applications must be submitted in Form AD through the clearing corporation, which must forward the application to the Board promptly and within thirty days of receipt.