Format of RSA key data SSL

After running NASSLX509Generate in what format is the key_data returned as? It does not appear to be PEM, NET, or DER, so what is it? I would like to not use NASSLX509Generate to generate my keys/certificates, but instead generate my own separately. When used with NASSLAccept or HSStartServerSecure etc…
Does anyone know what the format is?
Thanks,
–Troy