NOTE! This table is only applicable when using the M2 board as selected from the Tools -> Board menu from the Arduino IDE. See more information here.
Use the names in the "Mapped Pin Name" column in your Arduino Sketch.
A "pin mapping" describes how the different circuits of your M2 are connected to the processor. For example, the Green LED (DS6 on the schematic) is connected to pin 7 (AKA PA14) of the processor. To make things easier from a programming standpoint, we can map this to a pin name, in this case, the green LED is mapped to the name DS6 (which is compiled to the value 18).