They update the rules every three years, and often make new rules based on specific circumstances. They used to allow commercial tow trucks to be called, but Bill Fowler used one about five times one year, so "The Fowler Rule" was adopted.

After we took Darren's Charger through tech on a trailer in 2012, they adopted a rule that all vehicles must start on their own and run in tech. It's "The Gebhart Rule"...embarrassing!