STOCK-BASED COMPENSATION (Details) - USD ($) $ in Thousands	3 Months Ended
Aug. 31, 2021	Aug. 31, 2020
Total stock-based compensation	$ 588	$ 270
Cost of Sales
Total stock-based compensation	82	16
Selling, General and Administrative
Total stock-based compensation	395	205
Research and Development
Total stock-based compensation	$ 111	$ 49

Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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