[QUOTE=spacehorse;4125026]
Neck straps are legal for ALL phases. I use a racing yoke for dressage, and attach martingale as needed.[/QUOTE]
As in breastplate which is attached to the saddle and/or girth? http://www.bitofbritain.com/Breastplates_s/190.htm
Legal for all phases
Different from the OP’s question of a strap (normally leather) around the horse’s neck (NOT attached to saddle or girth) to steady the rider while jumping.
Also some use short strap in front of the saddle, connected to the d’s, in case their horse decides to go for a buck or bounce or fart/dart - this is also legal.