How to remap M5 $0 in Plasmac?

Hi, 
I understand that M3 and M5 commands are typically used for spindle control. However, in Plasmac, these commands have been remapped. For instance, M5 $0 is now used to stop the plasma cutting tool.
During the process of stopping the plasma cutting, certain events are indicated by M5 $0.

Could you kindly direct me to the file responsible for this remapping? This will allow me to customize the sequence of events according to my requirements.

Best regards
 

There is no remapping done, plasmac just reads the state of the hal pins spindle_M_on .