The term certIssuer is used to provide the OriginatorID of the initiator of the MMS connection.
As the term certIssuer may be (mis)understood as "certificate issuer", which would be the equivalent of an issuing certification authority, it is recommended to add a note to provide a hint that the certificate of the issuer of the MMS connection is meant.
It is not proposed to rename the term as this term is already used in several other documents. As IEC 62351-6 is a security focused document, adding a note would be sufficient.
Proposal
Proposal to include the following note below the second paragraph:
NOTE The term certIssuer refers to the certificate of the issuer (originator) of the MMS connection and is not to be understood as certificate issuer.