False Pin or schematic?

Hi, 
in pin_EINSYRAMBO line 139 
#define E_MUX2_PIN 78 // 84 in MK2 Firmware, with BEEPER as 78

But when you look at the board schematic the 78 is not connected, and the PJ5 : 76  is connected to P3-9...
So what is wrong the schematic or the pin definition?

https://nsa39.casimages.com/img/2018/07/30/180730054951220613.jpg
