IRCv3 extensions are a set of optional features for IRC servers and clients proposed by the IRCv3 Working Group
AdiIRC supports some of them and will enable any of these prefixes automatically if they are supported by the server.
server-time (added in 1.9.7)
sasl (added in 1.9.9)
tls (added in 1.9.9)
znc.in/server-time-iso (added in 1.9.7)
znc.in/server-time (added in 1.9.7)