sentences:  Top-level Canadian clubs either compete in the domestic Canadian Premier League (CPL), or Major League Soccer (MLS) of the United States.The Canadian Championship is the country's national cup and is contested between CPL teams, the Canadian teams of MLS and USL Championship (USLC), and the champions of League1 Ontario and the Première Ligue de soccer du Québec.For MLS teams, the Double may mean either the MLS Double, which is achieved by winning both the MLS Supporters Shield and the MLS Cup, or a league/cup Double of either the MLS Cup or Supporters Shield, in addition to the Canadian Championship.