X509
X.509 (International Telecommunication Union (ITU) standard) is primarily used to bind the identity to a person, organization or service and to an public-key which uses a digital signature. Although this program offers X.509 it is not primarily a feature of OpenPGP.It is just an added feature to the NexGen widget encryption software for user convenience.
However, OpenPGP is able to use the certificate but it may not look the way you want it to look in the OpenPGP Key Store but it will still work. Once again, is just an added feature that you can use but it is not part of the OpenPGP project so this is as is, I will make every attempt to remedy any issues that may be found but no guaranty.