I'd be more inclined to call it a protocol *variant* rather than "version".  I take it CFEngine started with classic and moved on to TLS, which is the sense in which it's a version,  but if I'm thinking of a protocol version it's which version of TLS are we using, for example; I expect "version" to look like "3.1" or "2.9.9", rather than "CLASSIC", "TLS", etc.