Geographic Information (Tables)

9 Months Ended

Feb. 28, 2018

Geographic Information Disclosure [Abstract]

Revenue from External Customers by Geographic Areas [Table Text Block]

	Nine Months Ended				Three Months Ended
	February 28, 2018		February 28, 2017		February 28, 2018		February 28, 2017
Revenues from sales to unaffiliated customers:
United States	$	533,000	$	743,000	$	208,000	$	345,000
Asia		2,112,000		1,740,000		626,000		448,000
Europe		1,562,000		1,672,000		485,000		654,000
South America		106,000		43,000		3,000		13,000
Middle East		115,000		127,000		54,000		37,000
Other		6,000		17,000		--		3,000
	$	4,434,000	$	4,342,000	$	1,376,000	$	1,500,000