If you had a business investment loss in 2011, you can deduct 1/2 of the loss from income. The amount of loss you can deduct from your income is called your allowable business investment loss (ABIL).
Complete Chart 6 of your T4037, Capital Gains guide to determine your ABIL.
On line 228, enter the gross business investment loss from line A of Chart 6.
On line 217, enter your allowable business investment loss from line D of Chart 6.