What is NSS?

Recently I've seen a couple things about low NSS horses. What does that mean?

NSS is Non-Specialty Stats, which affect showing and should be below 60 :) I'm sure someone else will be able to explain it better than me lol

NSS are the 3 stats not weighed as highly in shows as the 2 specialty stats each horse with a discipline has, for example a Racing horse would have Speed and Endurance as their specialty stats while Strength, Agility, and Intelligence would be their non-specialty stats. so a low NSS Racing horse would have very low Strength/Agility/Intelligence.
since having too many NSS makes it very difficult for a horse to win shows, people often breed to keep NSS down and lower it when possible.