KN sent as “dah-di-dah-dah-dit” is an invitation for named station to transmit.
Often it is sent when several stations are calling you and you have only understood a partial call from the mix.
e.g. M?0??F KN invites MM0FMF to reply or MW0AAF or anything with letters matching. It would be wrong for GM4TOE to reply as he has no matches just as MW0HGY does not end with an F.
I write as it would seem not all CW operators understand this. Which was why it took me 5mins to work HB9DAX with the QRM & QSB on the frequency along with the other station who just ignored the KN and sent his call. I think I tried 4 or 5 calls of HB9D?X KN before I could get the call from the QRM and QSB. HB9DAX was trying his best and this other station kept calling me over the top of him. Grrr!
Even if you don’t know what KN means, when a call is directed at something which does not match letters in your call it means you should SHUT UP AND NOT SEND till a general invite is made again. I was on the point of shutting down at this point but that would only punish the good ops. So I stayed active. But angry.