A RevocationReason indicates whether a Certificate has been revoked, and the reason for revocation. These correspond to standard revocation reasons from RFC 5280. Note that the enum labels and values in this definition are not the same ASN.1 values defined in RFC 5280. These values will be translated to the correct ASN.1 values when a CRL is created.

REVOCATION_REASON_UNSPECIFIED Default unspecified value. This value does indicate that a Certificate has been revoked, but that a reason has not been recorded.
KEY_COMPROMISE Key material for this Certificate may have leaked.
CERTIFICATE_AUTHORITY_COMPROMISE The key material for a certificate authority in the issuing path may have leaked.
AFFILIATION_CHANGED The subject or other attributes in this Certificate have changed.
SUPERSEDED This Certificate has been superseded.
CESSATION_OF_OPERATION This Certificate or entities in the issuing path have ceased to operate.
CERTIFICATE_HOLD This Certificate should not be considered valid, it is expected that it may become valid in the future.
PRIVILEGE_WITHDRAWN This Certificate no longer has permission to assert the listed attributes.
ATTRIBUTE_AUTHORITY_COMPROMISE The authority which determines appropriate attributes for a Certificate may have been compromised.