(RFC 4707 published April 2011, subtype last updated April 2011)

The IANA has registered the application/nasdata media type as defined
by the following information:

Media type name:     application
Media subtype name:  nasdata
Required parameters: none
Optional parameters: level

                     The NAS protocol level number for the enclosed
                     NAS data package.  If not present, the
                     protocol level defaults to 1.

Encoding scheme: NAS data is plain text; no special encodings are
needed.

Security considerations: see below

Security Considerations

Security issues are only addressed in respect to server-server
communication in this protocol level.  Username and password
combinations in the GETA and GETP commands can be used to make sure
that connections are only accepted from authorized clients.  PGP keys
according to [RFC2440] are used to sign NAS data in server-server
communication in order to validate that the data is authentic and has
not been tampered with.

Every server does have the possibility (in both server-server and
server-client communication) to deny some commands or the whole
connection according to the client's IP number.

No mechanisms are defined in the current protocol level to allow a
client to validate that it is talking to a legitimate server or that
the data it receives is authentic.

A stronger authentication scheme will be provided in a higher
protocol level.