SHAREHOLDERS' EQUITY (Tables)

12 Months Ended

May 31, 2021

Stockholders' Equity Note [Abstract]

Share-based Payment Arrangement, Option, Activity [Table Text Block]

	NUMBER OF STOCK OPTIONS	EXCERCISE PRICE RANGE PER SHARE	WEIGHTED AVERAGE EXERCISE PRICE
Options outstanding at May 31, 2019	1,476,209	$0.82-$3.90	$	2.07
Options granted	517,500	$2.68-$8.18	$	4.47
Options excercised	(137,958)	$0.82-$3.90	$	1.64
Options canceled or expired	(66,500)	$0.85-$8.18	$	3.43
Options outstanding at May 31, 2020	1,789,251	$0.82-$8.18	$	2.75
Options granted	430,616	$5.14-$8.70	$	6.73
Options excercised	(86,750)	$0.82-$3.62	$	1.20
Options canceled or expired	(51,751)	$2.35-$8.18	$	4.77
Options outstanding at May 31, 2021	2,081,366	$0.82-$8.70		$1.20 - $6.73

Schedule of Nonvested Share Activity [Table Text Block]

	Number of  shares	Stock options weighted average grant date fair value
Non-vested shares at May 31, 2020	822,584	$	3.78
Granted	430,616		6.73
Vested	(409,459)		3.36
Forfeited	(50,500)		4.80
Non-vested shares at May 31, 2021	793,241	$	5.54

Share-based Payment Arrangement, Option, Exercise Price Range [Table Text Block]

RANGE OF EXERCISE PRICES	NUMBER OUTSTANDING MAY 31, 2021	WEIGHTED AVERAGE REMAINING CONTRACTUAL LIFE IN YEARS	WEIGHTED  AVERAGE EXERCISE PRICE	NUMBER EXCERCISABLE AT MAY 31, 2021	WEIGHTED AVERAGE EXERCISE PRICE
$0.82-$1.04	216,000	3.75	$0.82	216,000	$0.82
$1.20-$2.81	1,024,500	6.45	$2.17	795,250	$2.02
$3.62-$8.70	840,866	8.00	$6.03	276,875	$4.54