That's an interesting question, because I myself looked at that when the issue resurfaced several months ago. I was a bit surprised to hear that. I should not have been surprised, but there are elements other than pure DND spending.
For example, there are veterans pensions and benefits—some benefits are included. There are some expenditures by the RCMP—not all, but a small fraction. There is spending by the Canadian Coast Guard, because in many countries the coast guard is considered a paramilitary force, so Canada is allowed, under NATO rules, to include expenditures by the Coast Guard, as well as some transfer payments to NATO and other international organizations.