The 2013 annual report of Gildan Activewear Inc., a Canadian company, contained the following excerpt in the "Independent Auditors' Report of Registered Public Accounting Firm":
We also have audited, in accordance with the standards of the Public Company Accounting Oversight Board (United States), the company's internal control over the financial reporting as at September 29, 2013 ...
Why is this a requirement of a Canadian company?