10. STOCKHOLDERS' EQUITY, COMPREHENSIVE INCOME AND STOCK-BASED COMPENSATION (Details Narrative) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	May 31, 2018	May 31, 2017	May 31, 2016
Total intrinsic values of options exercised	$ 1,058	$ 810	$ 185
Weighted average contractual life of the options exercisable and expected to be exercisable	3 years 3 months 14 days
Exercisable options to purchase	2,312,000	2,422,000	2,390,000
Weighted average exercise prices	$ 1.89	$ 1.63	$ 1.49
Restricted Stock Units granted	64,000	74,000	35,000
Market value on the date of the grant	$ 3.93	$ 1.68	$ 2.16
RSUs vested	16,000	42,000	35,000
RSUs cancelled	33,000
RSUs unvested	47,000	32,000
Intrinsic value of RSUs, nonvested	$ 122	$ 145
Intrinsic value of RSUs, vested			$ 35
2016 Equity Incentive Plan
Unrecognized stock-based compensation	976
Estimated forfeitures of unvested stock based awards, amount	$ 2
Weighted average period for recognition of costs	2 years 6 months
Shares reserved for issuance	2,238,000
Authorized shares	4,718,000
Outstanding shares	2,906,000
Employee Stock Purchase Plan
Stock-based compensation related to the ESPP	$ 290	$ 115	122
Unrecognized stock-based compensation	$ 306
Weighted average period for recognition of costs	1 year 3 months 18 days
Shares issued under ESPP plan	1,355,000
ESPP Shares available for issuance	145,000
Shares reserved under ESPP in October 2016		532,000
Maximum number of shares a participant may purchase	3,000
Maximum calendar year contribution per employee	$ 25	$ 25	$ 25
ESPP purchase right granted	359,000	1,000	304,000
ESPP shares issued	237,000	151,000	86,000
2006 Equity Incentive Plan
Shares remained available under plan	1,438,000
2006 Stock Option Plan and 2016 Equity Incentive Plan
Authorized shares		5,275,000
Outstanding shares		3,105,000
Board Of Directors
Restricted Stock Units granted		83,000
Market value on the date of the grant		$ 1.86
Stock Option and RSU Transactions
Stock-based compensation expense related to stock options and RSUs	$ 706	$ 884	$ 894