2. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details Narrative) - USD ($)	12 Months Ended
Apr. 30, 2018	Apr. 30, 2017	Apr. 30, 2016	Apr. 30, 2015
Cash and cash equivalents	$ 42,265,000	$ 46,799,000	$ 61,412,000	$ 68,001,000
Restricted cash pledged as collateral	1,150,000	1,150,000
Allowance for doubtful accounts - other receivables	0	0
Idle capacity costs	$ 13,966,000	$ 0	$ 0
Estimated useful lives of property and equipment	3 to 10 years
Concentration risk percentage	100.00%	100.00%	100.00%
Accounts Receivable [Member] \| Six Customers [Member]
Concentration risk percentage	93.00%	93.00%

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