5. ACCOUNTS RECEIVABLE (Details) - USD ($) $ in Thousands	12 Months Ended
	May 31, 2018		May 31, 2017	May 31, 2018	May 31, 2017
Receivables [Abstract]
Accounts receivable, gross				$ 2,860	$ 4,071
Less: Allowance for doubtful accounts	$ (61)		$ (61)	(4)	(61)
Accounts receivable, net				$ 2,856	$ 4,010
Allowance for doubtful accounts, Beginning	61		8
Allowance for doubtful accounts, Additions charged to costs and expenses	4		53
Allowance for doubtful accounts, Deductions	(61)	[1]	0
Allowance for doubtful accounts, Ending	$ 4		$ 61

[1] Deductions include write-offs of uncollectible accounts, collections of amounts previously reserved, and releases of allowance for doubtful accounts credited to expense.