4. EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Nov. 30, 2020	Nov. 30, 2019	Nov. 30, 2020	Nov. 30, 2019
Net (loss) income per share:
Numerator: Net (loss) income	$ (1,966)	$ 251	$ (1,859)	$ (162)
Denominator for basic net (loss) income per share: Weighted average shares outstanding (in thousands)	23,396	22,823	23,322	22,765
Shares used in basic net (loss) income per share calculation (in thousands)	23,396	22,823	23,322	22,765
Effect of dilutive securities (in thousands)	0	89	0	0
Denominator for diluted net (loss) income per share (in thousands)	23,396	22,912	23,322	22,765
Basic net (loss) income per share	$ (0.08)	$ 0.01	$ (0.08)	$ (0.01)
Diluted net (loss) income per share	$ (0.08)	$ 0.01	$ (0.08)	$ (0.01)