A healing scab is fine, but if there is flowing blood, the current rules state that you will be automatically eliminated.
NOW, the FEI wants to create a 'grey area' where stewards may investigate (put in simple terms) where the blood is coming from and how it was caused.
If blood is sighted in the warmup, this is when the warning will occur, the horse may continue warming up but if the blood has not stemmed by the time they are about to go into their test, they can be eliminated.
In some aspects, this could be a good thing - poor Adelinde's horse Parzival bit his tongue at WEG last year and was eliminated. It was not caused through cruelty or bad riding. The changed rule could have allowed her to compete without elimination.
HOWEVER, I feel that if they open a small loop hole in the current rule of eliminating for any blood, then his loop hole will be torn bigger and bigger to allow riders to 'slip through the cracks'. Many stewards feel intimidated by the big name riders and as a result, these riders may get away with blood that would have otherwise had them eliminated. It will be extremely hard to govern this small loop hole in the rule. Therefore, it is my opinion that an overall blood ban, as is current ruling, should remain as is. If there is no loop hole, there is no room for digression and bullying of those trying to enforce the ruling and make decsions on the spot at big time competitions and no one can slip through the cracks.