The following has been updated and is available on the CBSA website:
Memorandum D10-14-27, Tariff Classification of Front-mount Mowers
http://www.cbsa-asfc.gc.ca/publications/dm-md/d10/d10-14-27-eng.html

This memorandum has been updated to reflect changes made in the Customs Tariff. Other editing revisions made in this memorandum do not affect or change any of the existing policies or procedures.