Mass shootings are firearm-related violence with at least four casualties.
Excluded are shootings associated with acts of war, such as the 1944 Cowra breakout, which saw over 200 soldiers killed.
Also excluded are massacres of Aboriginal people using firearms, most of which are not well-documented.
That treatment of perpetrator casualties is at variance to some but not all definitions of a mass shooting used in the United States.
However, the above treatment is consistent with that used in other Wikipedia lists of mass shootings by country.