It Pays to Know the Rules

I'm familiarizing myself with the most current USEF Rule Book for dressage. It's a dry read but very useful.
Some interesting rules I didn't know: blind horses are eligible to compete in all regular dressage tests but not in a group of horses such as in quadrille, and if you see a rider wearing a red armband at a competition that means the rider is blind or visually impaired.