In a nutshell: The company in question changed its reporting standards in 2011. Furthermore, in order to maintain an "apples-to-apples" comparison between 2011 and 2010 results, the results for 2010 had to be restated according to the new reporting standards.
See page 23 of their 2011 Annual Report (PDF). Quote:
Transition to International Financial Reporting Standards
Canadian GAAP has been revised to incorporate International Financial
Reporting Standards (“IFRS”) and publicly traded companies like the
Corporation are required to apply such standards for years beginning
on or after January 1, 2011. Note 26 to the attached audited
consolidated financial statements discloses the impact of the
transition to IFRS on the Corporation’s reported financial position,
income and cash flows, including the nature and effect of changes in
accounting policies from those used in the Corporation’s audited
consolidated financial statements for the year ended December 31, 2010
which were prepared in accordance with Canadian GAAP prior to the
transition to IFRS.
Financial measures for the year ended December 31, 2010 reported in
this MD&A as comparative figures have been adjusted to reflect the
transition to IFRS, as have the financial measures for all 2010
quarters reported in the summary of quarterly results on page 34. The
accounting policies applied in these audited consolidated financial
statements are based on IFRS as issued, outstanding and effective on
February 23, 2012.
[... more details in annual report ...]