Condensed Consolidated Balance Sheets - USD ($)	Feb. 28, 2022	May 31, 2021
Current assets:
Cash and cash equivalents	$ 20,251,643	$ 20,581,604
Short-term investments	1,101,705	1,097,012
Accounts and other receivables, net	5,268,164	4,120,564
Inventory	5,932,166	5,835,596
Costs and estimated earnings in excess of billings	1,321,412	1,499,604
Other current assets	868,300	977,525
Total current assets	34,743,390	34,111,905
Maintenance and other inventory, net	1,477,678	1,612,839
Property and equipment, net	9,558,038	9,816,594
Other assets	204,216	200,538
Deferred income taxes	190,115	190,115
Total assets	46,173,437	45,931,991
Current liabilities:
Accounts payable	1,170,172	1,787,325
Accrued commissions	353,245	269,064
Billings in excess of costs and estimated earnings	708,129	1,361,985
Other current liabilities	2,281,196	1,715,409
Total current liabilities	4,512,742	5,133,783
Stockholders' Equity:
Common stock and additional paid-in capital	10,249,834	10,111,735
Retained earnings	34,325,863	33,601,475
Stockholders’ equity before treasury stock	44,575,697	43,713,210
Treasury stock - at cost	(2,915,002)	(2,915,002)
Total stockholders’ equity	41,660,695	40,798,208
Total liabilities and stockholders’ equity	$ 46,173,437	$ 45,931,991