Hi guys, and thank you.
After digging around a bit more, the file is OSO001.msg, and the keys seem to be in the very first message, aka #0. These can be retrieved f.e. with some very simple REXX:
/* Get localized equivalents of single confirmation keys and such */
if RxFuncQuery('SysLoadFuncs') then do
call RxFuncAdd 'SysLoadFuncs','RexxUtil','SysLoadFuncs'
call SysLoadFuncs
end
keys = SysGetMessage(0,'OSO001.MSG')
say keys
exit
and naturally you get "Y N A R I" for English, or "S N C R I" for Spanish, and so on.
I got a little worried when I found out the script above yields "Y N A R I" again for Japanese, or "1 2 1 2 3" for Russian, but apparently that is indeed how those work. Trying to format floppies from the command line, which involves this kind of simple confirmation, matches the values contained in the message on a Russian or Japanese system, see screenshots below: