Sorry, I do not know. But, if your ST is French it would translate to "Trip A" or "Journey A". As in your odometer Trip A selection for a certain trip to keep track of that mileage. If you know what I mean.
I don't speak French. But, that's my best guess. ...I'm a chef. I understand a very tiny bit of french. Mostly food words.
This is probably not the correct answer for this. I just thought it was interesting. Sorry