for Chopard and the practice pre-dates the current crop of L.U.C. movements.
It was an early 'logo' of Louis-Ulysse Chopard and has been used almost interchangeably with the 'Chopard signature'. It has found its way back onto the winding micro-rotors of the x.96 movements instead of the Chopard cursive signature...oooer....that caused some rancour amongst the fans, I can tell you!
Regards,
MTF