Here is the official policy of the TSX:

http://www.tmx.com/en/pdf/SBCA_guide.pdf

Section 613(h)(i) requires that the exercise price for any stock options not be less than market price. Market price is defined in Part 1 of the TSX Company Manual as the five-day volume weighted average trading price, which is calculated by dividing the total value by the total volume of securities traded for the relevant period.

However, TSX will accept, as theexercise price for stock options and other awards: (a) a closing market price at the time of the grant; or (b) a reasonable pre-determined formula, based on a weighted average trading price or average daily high and low board lot trading prices for a short period of time prior to the time of the grant.