Hello,
The landing/taxi light switch, labelled A-ATT-ROUL (from aft to front) does not function in this order.
When this switch is placed at ATT (aterrisage, landing), the projected light is angled more towards the ground, i.e. as a taxiing light.
When this switch is placed at ROUL (roullage, taxiing), the projected light is angled more forwards, i.e. as a landing/takeoff light.
In the Mirage 2000C, the same switch is labelled A-ROUL-ATT (from aft to front).