Note 9 - Capital Transactions - Warrant Activity (Details) - $ / shares	12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Outstanding (in shares)	85,843,036	84,538,161
Warrants issued (in shares)	2,095,333	43,493,809
Warrants issued, exercise price (in dollars per share)	$ 0.10	$ 0.10
Warrants exercised (in shares)	(9,697,146)	(35,798,809)
Warrants expired/cancelled (in shares)	(3,116,550)	(6,390,125)
Outstanding (in shares)	75,124,673	85,843,036
Minimum [Member]
Warrants exercised, exercise price (in dollars per share)		$ 0.030
Warrants expired/cancelled, exercise price (in dollars per share)		0.60
Maximum [Member]
Warrants exercised, exercise price (in dollars per share)		0.035
Warrants expired/cancelled, exercise price (in dollars per share)		$ 0.90