11. STOCKHOLDERS' EQUITY, COMPREHENSIVE INCOME AND STOCK-BASED COMPENSATION (Details Narrative) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	May 31, 2020	May 31, 2019	May 31, 2018
Total intrinsic values of options exercised	$ 160	$ 338	$ 1,058
Weighted average contractual life of the options exercisable and expected to be exercisable	3 years 8 months 8 days
Exercisable options to purchase (in thousands)	2,203	2,314	2,312
Weighted average exercise prices	$ 2.25	$ 2.14	$ 1.89
Restricted Stock Units granted (in thousands)	10	0	64
Shares withheld for taxes and not issued (in thousands)	6
Market value on the date of the grant	$ 1.64		$ 3.93
RSUs vested (in thousands)	13	16	16
RSUs unvested (in thousands)	10	23	47
Intrinsic value of RSUs, nonvested	$ 16	$ 40	$ 122
Stock Option and RSU
Stock-based compensation expense related to stock options and RSUs	751	$ 650	$ 706
RSUs cancelled (in thousands)		8	33
2016 Equity Incentive Plan
Unrecognized stock-based compensation	1,131
Estimated forfeitures of unvested stock based awards, amount	$ 3
Weighted average period for recognition of costs	2 years 7 months 6 days
Shares reserved for issuance (in thousands)	3,435
Authorized shares (in thousands)	4,813	4,277
Outstanding shares (in thousands)	3,163	3,129
Employee Stock Purchase Plan
Unrecognized stock-based compensation	$ 59
Weighted average period for recognition of costs	9 months 18 days
Stock-based compensation related to the ESPP	$ 159	$ 255	$ 290
Maximum calendar year contribution per employee	$ 25	$ 25	$ 25
Maximum number of shares a participant may purchase (in thousands)	3	3	3
ESPP purchase right granted (in thousands)	55	379	359
ESPP shares issued (in thousands)	136	125	237
Total shares issued under ESPP plan (in thousands)	1,617
ESPP Shares available for issuance (in thousands)	233
2006 Equity Incentive Plan
Shares remained available under plan (in thousands)	1,835
Board Of Directors
Restricted Stock Units granted (in thousands)	9	0	0
Market value on the date of the grant	$ 1.64