Hasn't the ACARS been done to death by now......
Stickyb...
would seem to have been truncated after the comma
The clue is probably in the words "libellé succint du message".
i.e. an abbreviation / brief summary / however you want to put it of the actual message. I would guess any truncations were intented and designed by a large commitee at Airbus, so I would suggest no need to start playing the X-Files theme tune.