Location of the buttons in the field of view. Note: the buttons move over the year and did not remain in the same position over time ! In the image ibuttons_chains_location_2020-2021.jpg: BT7 : from top to bottom, starting at the float 58, 59, 61, 62, A BT6: from top to bottom, starting at the float 54, 55, 74, B, J BT10: from top to bottom, starting at the float G, 57, 53 (no data), 51, 49 BTI1: from top to bottom 48, starting at the float C, D, E F