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2. STOCK-BASED COMPENSATION (Details 1) (Stock Options, USD $)	3 Months Ended		9 Months Ended
	Feb. 28, 2013	Feb. 29, 2012	Feb. 28, 2013	Feb. 29, 2012
Stock Options
Expected term (in years)	5 years	5 years	5 years	5 years
Volatility	0.94%	0.85%	0.91%	0.83%
Expected dividend	$ 0	$ 0	$ 0	$ 0
Risk-free Interest Rates	0.76%	0.84%	0.72%	1.14%
Estimated Forfeiture Rate	0.25%	0.25%	0.25%	0.25%
Weighted Average Grant Date Fair Value	$ 0.62	$ 0.43	$ 0.78	$ 0.59

The estimated measure of the percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period.

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