12. STOCK-BASED COMPENSATION (Details 4) $ / shares in Units, $ in Thousands	3 Months Ended
	Aug. 31, 2019 USD ($) $ / shares shares
$0.80-$0.97
Options outstanding, ending (in thousands) | shares	47
Weighted average remaining contractual life (years) options outstanding	3 months 4 days
Weighted average exercise price outstanding, ending | $ / shares	$ .85
Options exercisable shares, ending (in thousands) | shares	47
Weighted average remaining contractual life (years) options exercisable	3 months 4 days
Weighted average exercise price for options exercisable, ending | $ / shares	$ .85
$1.09-$1.28
Options outstanding, ending (in thousands) | shares	301
Weighted average remaining contractual life (years) options outstanding	9 months 25 days
Weighted average exercise price outstanding, ending | $ / shares	$ 1.28
Options exercisable shares, ending (in thousands) | shares	301
Weighted average remaining contractual life (years) options exercisable	9 months 25 days
Weighted average exercise price for options exercisable, ending | $ / shares	$ 1.28
$1.64-$2.06
Options outstanding, ending (in thousands) | shares	1,261
Weighted average remaining contractual life (years) options outstanding	5 years 4 months 2 days
Weighted average exercise price outstanding, ending | $ / shares	$ 1.76
Options exercisable shares, ending (in thousands) | shares	483
Weighted average remaining contractual life (years) options exercisable	3 years 6 months 14 days
Weighted average exercise price for options exercisable, ending | $ / shares	$ 1.80
$2.10-$2.81
Options outstanding, ending (in thousands) | shares	1,584
Weighted average remaining contractual life (years) options outstanding	3 years 3 months 18 days
Weighted average exercise price outstanding, ending | $ / shares	$ 2.43
Options exercisable shares, ending (in thousands) | shares	1,263
Weighted average remaining contractual life (years) options exercisable	2 years 7 months 17 days
Weighted average exercise price for options exercisable, ending | $ / shares	$ 2.44
$3.46-$3.93
Options outstanding, ending (in thousands) | shares	241
Weighted average remaining contractual life (years) options outstanding	4 years 10 months 28 days
Weighted average exercise price outstanding, ending | $ / shares	$ 3.85
Options exercisable shares, ending (in thousands) | shares	151
Weighted average remaining contractual life (years) options exercisable	4 years 11 months 8 days
Weighted average exercise price for options exercisable, ending | $ / shares	$ 3.80
$.80-$3.93
Options outstanding, ending (in thousands) | shares	3,434
Weighted average remaining contractual life (years) options outstanding	3 years 10 months 24 days
Weighted average exercise price outstanding, ending | $ / shares	$ 2.16
Options exercisable shares, ending (in thousands) | shares	2,245
Weighted average remaining contractual life (years) options exercisable	2 years 8 months 8 days
Weighted average exercise price for options exercisable, ending | $ / shares	$ 2.20
Aggregate intrinsic value for options exercisable | $	$ 41