SC-XX: Process RFC 8657 CAA Parameters

docs/BR.md

@@ -1082,6 +1082,11 @@ CAs MAY check CAA records at any other time.
 
 When processing CAA records, CAs MUST process the issue, issuewild, and iodef property tags as specified in RFC 8659, although they are not required to act on the contents of the iodef property tag. Additional property tags MAY be supported, but MUST NOT conflict with or supersede the mandatory property tags set out in this document. CAs MUST respect the critical flag and not issue a certificate if they encounter an unrecognized property tag with this flag set.
 
+EFFECTIVE DD-MM-YYY:
+When processing CAA records, CAs MUST process the accounturi and validationmethods parameters as specified in RFC 8657. In addition:
+* When the certificate request does not use the ACME protocol defined in RFC 8555, the CA MUST define the recognized format of the accounturi in their CPS.
+* The CA MUST only recognize validationmethods parameters in the format "tlsbr-" + the 3.2.2.4 subsection number that defines the permitted validation method, e.g. "tlsbr-18" represents Agreed-Upon Change to Website v2.
+
 If the CA issues a certificate after processing a CAA record, it MUST do so within the TTL of the CAA record, or 8 hours, whichever is greater.
 
 RFC 8659 requires that CAs "MUST NOT issue a certificate unless the CA determines that either (1) the certificate request is consistent with the applicable CAA RRset or (2) an exception specified in the relevant CP or CPS applies." For issuances conforming to these Baseline Requirements, CAs MUST NOT rely on any exceptions specified in their CP or CPS unless they are one of the following: