r]eferring to the delimitation determined by the Arrêté of 31 August 1927 (Erratum) between Dori and Téra, . . . to visit the site in order to observe the placement of said land in relation to the above-mentioned boundary.
[ . . .] in order to prevent any similar further territorial disputes in this area, we have established a marker designed to fix the boundary between Dori and Téra, the boundary in principle following a notional straight line starting from the Tong-Tong astronomic marker and running to the Tao astronomic marker.
The Ouiboriels [Vibourié according to Niger] marker being located on this notional line . . .”360