During my 1970 ETPS course "incidence" and angle of attack were used interchangeably, particularly so during aerodynamics and stability and control lectures. We all knew what was meant, in a long lesson with dozens of references "incidence" is just easier. During visits to manufacturers, "incidence" was the common term. Might have just been an aerodynamicists thing. D. P. Davies also used incidence when visiting as a guest speaker. Even the Mirage 111 AOA indicator was referred to as the incidence indicator.