Exactly what makes a MOPAR a "Matching Numbers" car?

I call my car numbers matching. I would say it's actually about 60% there. But the M/T is correct to the car. I won't cut it up but if someone else purchased it and turned it into a race car it's your car, your way.....

But if you really want my honest opinion and I have always thought this is the moment any single item is changed on the car from the moment you sign the papers for ownership it is no longer original. That includes Air filter, oil, and on down the line. But my opinion is like #$%holes and everyone has one!