Usually HR means heart rate. I ride endurance, have a heart rate monitor HRM and those looks like heart rates to me. Not sure what work the horse was doing. But as a reference guide, my arab gelding can trot at 110 bpm (beats per minute) and go about 7- 8 mph. Hills maybe 125-130. Canter work maybe up to 140 bmp depending on terrain. If the horse is fit, and sound the heart rate drops very quickly when work is stopped. And it doesn't go up very fast when put back to work. If it does, the horse is not as fit as you think. Remember, heart and lungs get fit fast, like 30 days, it is the bones and tendons that take a year or more. So sometimes you will see great heart rates and think the horse is fit and frisky, but use caution, the bones and tendons go at a much slower rate, and damage can occur. When ya ride endurance you learn alot about heart rates in horses. For the record, I do not use a hrm (heart rate monitor) and a speedometer. I don't ride very often with one, I use it as a guide, and not all do that.
I believe it means that the stallion did not finish the test, but the Dressage and jumping scores are based on performance during the "almost 70" days of the test. So, no official placement, but scores do indicate indexed performance .
Avagon did very well a couple years ago, but did not complete his final test day, so was listed "HR"
Yes - sunnydays is correct.
It means the horse did not compete in the final days of the testing but was given a score based on his performance up until that time. HR - means "not ranked". If the stallions don't compete on the final 3 days they don't get ranked/placed in the final order for the winner/runner up etc. They just get their scores.
Has nothing to do with heart rate.