ID : 1.3.6.1.4.1.1466.115.121.1.8
Because of the changes from X.509(1988) and X.509(1993) and additional changes to the ASN.1 definition to support certificate extensions, no string representation is defined, and values in this syntax MUST only be transferred using the binary encoding, by requesting or returning the attributes with descriptions "userCertificate;binary" or "caCertificate;binary". The BNF notation in RFC 1778 for "User Certificate" is not recommended to be used.
BNC Syntax: 1.3.6.1.4.1.1466.115.121.1.8 DESC 'Certificate'
rfc2252