I remember both the old man and self being puzzled by a response from (I think) Koper harbour authority in 1972. It was MIJMA.
The puzzle has returned to me every now and again without remedy until last week. It is the 1931 International Signal code for "You have pratique". Volume II "For Radio Signalling"
It came to me as a surprise that there was an International code of Signals and that an update was produced in 1969. Whilst the update has ZY group for pratique granted rather than MIJMA I am not querying the delay in Yugoslavia taking up the new code (which Senegal list as still in use) but that there was a code at all. The only code I learned for my ticket was the Q code.
Anyone else in the same boat?