If you all will indulge me...
IRS auditor is examining the books of a large bakery operation. Flipping through the MTCs as they were called back then, he verifies their Machinery Tax Credits. Comes to a $6 million fridge. Tells taxpayer he's gonna have to see this fridge. Controller asks him to come to the window where his attention is directed to the building across the way. "That's the fridge," he tells the auditor.
"Wait...you know the MTC does not apply to buildings!" the auditor protests. The controller explains the building is purpose-built. Loaves of bread are hot & moist, trucks have to loaded, loaves must hit the streets at certain temp/humidity. Eureka! We load the trucks and park them in the fridge, bread hits the street perfectly.
The auditor has to think this over: is the fridge a piece of machinery or real property? Finally he turns to the controller and asks, "Does the light come on when you open the door?"
Controller says, "Follow me." They go down the steps, across the courtyard, to the fridge. Controller hits a button, doors open, lights come on.
MTC granted!