I have an answer from Serge Texier on "Master194":
"The Caudron G 3 and G 4 did not have an aileron, the warping was obtained by deformation of the external part of the upper wings,
The lacing you are talking about allows the "flexible" connection of the wing sections subjected to torsion by cables connected to the pilot's stick,
This lacing also allows to adjust the tension of the covering at the trailing edge of the external part of the wing, this lacing cannot be "tight" as some claim, because the torsion effect would be limited,
The only G 3 on which I flew in Besançon in 1971, the one in Salis, did not have a canvas to hide the lacing"
So I will put the lacing and below the canvas...
