3.2.1.4.2.1.4.2 Processing Rules for Renewing a Certificate Request
A request to renew an existing certificate MUST use one of the following formats, as specified in section 2.2.2.6:
CMS with embedded PKCS #10.
CMS with embedded CMC.
Rules specified in the following sections MUST be used by the CA to process the certificate request for each of the preceding formats.