[rjsimmon]

From posts I’ve gotten the “K” and “W” were later editions.

How much later is later?

"By 1912, the need to quickly identify stations operated by multiple companies in multiple nations required an international standard; an ITU prefix would be used to identify a country, and the rest of the call sign an individual station in that country."

Call Signs

[SkyDancer]

Dunno - was told “later they added a dividing line”