Encoding a chain of certificates in ByteString data type|OPC UA Standard|Forum|OPC Foundation

IMHO there seems to be an inconsistency in encoding of a chain of certificates in “OPC UA part 12 v1.04”

• “Section 7.5.5 AddCertificate” specifies a method of TrustList Type to allow a client to add a single certificate to a Trust List. It is there stated that “If the Certificate is issued by a CA then the Client shall provide the entire chain in the certificate argument”. In this case a chain of certificates is passed as a single ByteString to the method.
• “Section 7.7.4 UpdateCertificate” specifies a method of ServerConfiguration Type to allow a client to update a certificate to a server. This method accepts issuer certificates as an array of ByteString. These issuer certificates are needed for verification of the certificate to update and hence can also contain a chain of certificates e.g., in multi-level PKI.

My question here is what should be the expected way to encapsulate a chain of certificates from OPC UA’s perspective? A chain per single ByteString variant or by means of an array of ByteString variants? Or both of them are accepted?

Thanks!