Note 5 - Intangible Assets (Tables)

12 Months Ended

Mar. 31, 2019

Notes Tables

Schedule of Finite-Lived Intangible Assets [Table Text Block]

	March 31, 2019									March 31, 2018
	Cost		Weighted Average Amortization Period (Years)		Accumulated Amortization			Net Carrying Amount		Cost		Weighted Average Amortization Period (Years)		Accumulated Amortization			Net Carrying Amount
Patents & Trademarks	$	20,934		15		(12,035	)	$	8,899	$	20,934		15		(10,639	)	$	10,295

Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block]

For the fiscal years ended March 31,
2020	$	1,396
2021		1,396
2022		1,396
2023		1,396
2024		1,396
Thereafter		1,919
	$	8,899