Netscape MANAGEMENT SYSTEM 6.1 - ADMINISTRATOR Administrator's Manual page 733

Standard X.509 v3 Certificate Extensions
PKIX requires this extension for entities that are identified by name forms other
than the X.500 distinguished name (DN) used in the subject field. PKIX Part 1
describes additional rules for the relationship between this extension and the
subject field.
Email addresses may be provided either in the Subject Alternative Name
extension, the certificate subject name field, or both. If the email address is
provided as part of the subject name, it must be in the form of the
EmailAddress
attribute defined by PKCS-9. Software that supports S/MIME must be able to read
an email address from either the Subject Alternative Name extension or from the
subject name field.
CMS Version Support
Supported since CMS 4.1. Refer to "SubjectAltNameExt" on page 557.
subjectDirectoryAttributes
OID
2.5.29.9
Criticality
PKIX Part 1 requires that this extension be marked noncritical.
Discussion
The Subject Directory Attributes extension conveys any desired directory attribute
values for the subject of the certificate. It is not recommended as an essential part of
the proposed PKIX standard, but may be used in local environments.
CMS Version Support
Supported since CMS 4.2. Refer to "SubjectDirectoryAttributesExt" on page 561.
subjectKeyIdentifier
OID
2.5.29.14
Criticality
This extension is always noncritical.
Appendix G Certificate and CRL Extensions 733