v2.5.6 and v2.5.5

[Michael Hipp]

The announcement for v2.5.6 says:

"Combining "::" syntax with the -rsh/-e option now uses the
specified remote-shell as a transport to talk to a (newly-spawned)
server-daemon.  This allows someone to use daemon features, such
as modules, over a secure protocol, such as ssh.  (JD Paul)"

Do both the client and server have to be v2.5.6 for this to work?
Or only the server? Or only the client?

Thanks,
Michael Hipp