Geographic Information (Tables)

9 Months Ended

Feb. 29, 2020

Geographic Information Disclosure [Abstract]

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

	Nine Months Ended				Three Months Ended
	February 29, 2020		February 28, 2019		February 29, 2020		February 28, 2019
Revenues from sales to unaffiliated customers:
United States	$	389,000	$	423,000	$	165,000	$	141,000
Asia		1,863,000		1,973,000		404,000		653,000
Europe		1,226,000		1,330,000		509,000		416,000
South America		166,000		129,000		95,000		2,000
Middle East		313,000		180,000		4,000		49,000
Other		11,000		--		--		--
	$	3,968,000	$	4,035,000	$	1,177,000	$	1,261,000