2.2 Message Syntax
The extensions specified in this document use or reference messages documented in [RFC4217], [RFC2389], [RFC959], and [RFC2228]. The list of existing messages that relate to the File Transfer Protocol over Secure Sockets Layer is as follows:
AUTH TLS from [RFC4217]
PROT P from [RFC4217]
PBSZ 0 from [RFC2228] and [RFC4217]
CCC from [RFC4217]
REIN from [RFC959]
FEAT from [RFC2389]
The AUTH SSL message is introduced in this specification. This new message is fully synonymous with the existing AUTH TLS message.