7. INCOME TAXES (Details Narrative) - USD ($) $ in Thousands	12 Months Ended
	May 31, 2019	May 31, 2018	May 31, 2017	May 31, 2016
Valuation allowance	$ 813	$ (6,139)	$ 1,635
Unrecognized tax benefits	1,809	1,785	$ 789	$ 789
Federal refundable AMT credit		90
Reduction in deferred tax assets		$ (6,400)
Federal
Net operating loss carryforward	53,803
Research and development tax credit carryforwards	2,071
State
Net operating loss carryforward	29,504
Research and development tax credit carryforwards	5,609
Alternative minimum tax credit carryforwards	34
Foreign
Net operating loss carryforward	$ 345