One off the top of my head; 250-81 (1990 version) only allowed exothermic welding as a means to extend the GEC and only in industrial or commercial locations. I believe it was '93 that allowed irreversible compression-type-connectors and dropped the industrial and commercial location only requirement.(correct me if I am wrong. My '93 and '96 code books have grown legs.)
The 2002 code has relaxed the three story limit on NM cable.
If I think of more I'll post them later.
Nick
