Sellier construction is also rigid because an extra layer of leather is added to give the bag its stiffness and not solely from the stitching method. Retourne must be soft otherwise it would be impossible to turn it inside out. BTW, that's what retourne means "to flip over". Sellier means "saddle" which is the type of stitching used by Hermes, and for which its famous for.
RIGIDE vs. SOUPLE Kellys: I tried doing a search but couldn't find it, but sometimes people come on the board to ask for differences between a Kelly in the rigide (rigid) or souple (supple) constructions. Basically, rigide involves stitching on the outside. It is more difficult and therefore more expensive. Souple involves stitching in the inside then inverting the bag. Note that Hermes has introduced new terminology: Rigide is now Sellier and Souple is now Retourne.
IT WORKED!!!
thank you all. he understands now.