The Church of Saint-Léon-de-Westmount’s Parks Canada plaque.

Parks Canada has a “guarded” explanation of their plaques:

http://www.pc.gc.ca/eng/docs/pc/poli/princip/sec2/part2d/part2d6.aspx

“Aspects of Canadian history declared to be of national historic significance will normally be commemorated by a Ministerial plaque bearing the inscription of the Historic Sites and Monuments Board of Canada. A plaque is not a national historic site, although it may be erected at or on a national historic site. The existence of a Ministerial plaque at a site not administered by Parks Canada does not imply provision for protection or maintenance of the site by Parks Canada.”