7. INCOME TAXES (Tables)

12 Months Ended

May 31, 2017

Income Tax Disclosure [Abstract]

Domestic and foreign components of loss before income tax (expenses) benefit

    Domestic and foreign components of loss before income tax (expense) benefit are as follows (in thousands):

	Year Ended May 31,
	2017			2016			2015
Domestic	$	(5,663	)	$	(6,794	)	$	(6,871	)
Foreign		35			19			258
	$	(5,628	)	$	(6,775	)	$	(6,613	)

Income tax (expense) benefit

    The income tax (expense) benefit consists of the following (in thousands):

	Year Ended May 31,
	2017			2016			2015
Federal income taxes:
Current	$	—		$	—		$	—
Deferred		—			—			—
State income taxes:
Current		(8	)		3			(19	)
Deferred		—			—			—
Foreign income taxes:
Current		(17	)		(13	)		(15	)
Deferred		—			—			—
	$	(25	)	$	(10	)	$	(34	)

Income tax reconciliation

     The Company’s effective tax rate differs from the U.S. federal statutory tax rate, as follows:

	Year Ended May 31,
	2017			2016			2015
U.S. federal statutory tax rate		34.0	%		34.0	%		34.0	%
State taxes, net of federal tax effect		(0.1	)		—			(0.2	)
Foreign rate differential		0.1			0.2			1.4
Stock-based compensation		(2.8	)		(3.8	)		(2.2	)
Research and development credit		3.1			2.1			1.1
Change in valuation allowance		(33.8	)		(32.5	)		(34.4	)
Other		(0.9	)		(0.2	)		(0.2	)
Effective tax rate		(0.4	)%		(0.2	)%		(0.5	)%

Net deferred tax assets

      The components of the net deferred tax assets are as follows (in thousands):

	Year Ended May 31,
	2017			2016
Net operating losses	$	18,719		$	16,643
Credit carryforwards		4,715			4,430
Inventory reserves		870			1,064
Reserves and accruals		1,566			1,606
Other		393			885
		26,263			24,628
Less: Valuation allowance		(26,263	)		(24,628	)
Net deferred tax assets	$	—		$	—

Unrecognized tax benefits

    The Company maintains liabilities for uncertain tax positions. These liabilities involve considerable judgment and estimation and are continuously monitored by management based on the best information available. The aggregate changes in the balance of gross unrecognized tax benefits are as follows (in thousands):

Beginning balance as of May 31, 2014	$	973
Decreases related to prior year tax positions		—
Decreases related to lapse of statute of limitations		(54	)
Balance at May 31, 2015	$	919
Decreases related to prior year tax positions		(124	)
Decreases related to lapse of statute of limitations		(6	)
Balance at May 31, 2016	$	789
Decreases related to prior year tax positions		—
Decreases related to lapse of statute of limitations		—
Balance at May 31, 2017	$	789