why do we have a th on asx but not on tsx?

I find it very odd that EXT was placed in a TH on the ASX yesterday prior to open, but NOT on the TSX.

Just looked at the TSX, and current status of EXT was as follows:
Price $7.35 (+2.65%)
Low $7.00
High $7.48
Volume 3,582

This compares with price and volume data over the last couple of weeks for EXT in Canada:
Date Open High Low Close Volume Chg % Chg
04/29/2011 7.360 7.360 6.980 7.160 12,080 -0.590 -7.61%
04/28/2011 8.070 8.130 7.750 7.750 15,350 -0.950 -10.92%
04/26/2011 8.760 8.800 8.450 8.700 5,050 0.040 0.46%
04/25/2011 8.610 8.690 8.600 8.660 5,322 0.160 1.88%
04/21/2011 7.820 8.500 7.820 8.500 3,900 0.070 0.83%
04/20/2011 8.350 8.430 8.350 8.430 7,700 0.080 0.96%
04/18/2011 8.400 8.400 8.300 8.350 1,970 -0.150 -1.76%
04/15/2011 8.450 8.550 8.450 8.500 15,800 0.040 0.47%
04/14/2011 8.500 8.650 8.460 8.460 2,100 0.010 0.12%
04/13/2011 8.410 8.450 8.400 8.450 2,200 0.050 0.60%
04/12/2011 8.400 8.400 8.400 8.400 500 -0.600 -6.67%
04/11/2011 N/A N/A N/A 9.000 50 0.000 0.00%
04/08/2011 8.690 9.000 8.510 9.000 4,710 0.410 4.77%
04/07/2011 8.600 8.600 8.400 8.590 1,307 0.040 0.47%
04/06/2011 8.350 8.550 8.350 8.550 2,000 0.550 6.88%
04/05/2011 8.100 8.100 8.000 8.000 2,000 0.010 0.13%
04/04/2011 8.050 8.050 7.990 7.990 390 -0.060 -0.75%

My question is, given we are in a TH here in Australia, why is there no TH in Canada and what does the sp on TSX suggest?