Contains the certificates which have been used for the signature validation.
The following paragraphs were taken from the W3C note
"XML Advanced Electronic Signatures (XAdES)":
«In principle, the CertificateValues element contains the full set of certificates that have been used to validate the electronic signature, including the signer's certificate. However, it is not necessary to include one of those certificates into this property, if the certificate is already present in the ds:KeyInfo element of the signature. »
«In fact, both the signer certificate (referenced in the mandatory SigningCertificate property element) and all certificates referenced in the CompleteCertificateRefs property element must be present either in the ds:KeyInfo element of the signature or in the CertificateValues property element. »