[duncan1437]

the exemption is tariff item 9966.00.00, and here's the related Memorandum D10-15-20:

Interpretation of Tariff Item No.9966.00.00

edit: not sure, but the refund form might be a B2G:

all of the forms:

http://www.cbsa-asfc.gc.ca/publications/forms-formulaires/menu-eng.html

the B2G form and instruction sheet::

http://www.cbsa-asfc.gc.ca/publications/forms-formulaires/b2g.pdf

presumably the customs duty refund will trigger an (automatic) GST refund as well.......and allow an application for a PST refund too:

http://www.rev.gov.on.ca/en/forms/rst/pdf/0298.pdf