STOCKHOLDERS EQUITY AND STOCK-BASED COMPENSATION (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	May 31, 2022	May 31, 2021	May 31, 2020
Total stock-based compensation	$ 2,923	$ 1,101	$ 910
Effect on net loss per share, basic	$ 0.11	$ 0.05	$ 0.04
Effect on net loss per share, diluted	$ 0.11	$ 0.05	$ 0.04
Cost of Sales
Total stock-based compensation	$ 234	$ 70	$ 80
Selling, General and Administrative
Total stock-based compensation	1,721	816	631
Research and Development
Total stock-based compensation	$ 968	$ 215	$ 199