Lists all the object identifiers of the X509 extensions of the PKIX profile.
Extensions are addiitonal attributes which can be inserted in a X509 v3 certificate. For example a "Driving License Certificate" could have the driving license number as a extension.
Extensions are represented as a sequence of the extension identifier (Object Identifier), a boolean flag stating whether the extension is to be treated as being critical and the extension value itself (this is again a DER encoding of the extension value).
@see Extension
@author Amit Kapoor
@author Hemma Prafullchandra