It does so after sending "UHNAMES" in protoctl and getting a "UHNAMES" back from mIRC, which indicates support for n!u@h mask.
So, while 6.17 and later will get <level>n!u@h, 6.16 and earlier versions will get simply <level>nick.
Similar with NAMESX, which allows the server to send all levels (e.g. "@+nikb!nikb@staff.webchat.org" instead of simply "@nikb!nikb@staff.webchat.org"
Could I ask you to test this using arena.webchat.org, which runs a slightly newer build than the rest, and reports UHNAMES and NAMESX in its 005, because, I still don't see anything wrong with the CR side of this but obviously there's an issue somewhere -- whether it's in the output of CR, or in mIRC's parsing -- which must be addressed.
-n
