2. STOCK-BASED COMPENSATION (Details Narrative) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Feb. 29, 2016	Feb. 28, 2015	Feb. 29, 2016	Feb. 28, 2015
Stock-based compensation costs capitalized as part of inventory	$ 0	$ 53	$ 0	$ 53
Stock-based compensation expense related to stock options	190	182	708	589
Intrinsic value of options exercised	0	30	$ 185	466
Weighted average remaining contractual life of the options exercisable and expected to be exercisable			4 years 3 months 25 days
Employee Stock Purchase Plan
Stock-based compensation related to the ESPP	23	$ 37	$ 78	$ 104
Compensation cost related to purchase rights under the ESPP but not yet recognized	$ 51		$ 51
Weighted average period for recognition of costs			10 months 24 days
ESPP purchase rights granted	0	0	0	170,000
ESPP shares issued			36,000	43,000
ESPP shares available for issuance	232,000		232,000
1996 Stock Option Plan and 2006 Equity Incentive Plan
Unrecognized stock-based compensation	$ 1,270		$ 1,270
Estimated forfeitures of unvested stock based awards, amount	$ 3		$ 3
Weighted average period for recognition of costs			2 years 2 months 12 days
Restricted Stock Units
Restricted Stock Units granted			35,000
Market value on the date of the grant			$ 2.16