What is a notable characteristic of the Standardbred horse related to its registration?

The notable characteristic of the Standardbred horse related to its registration is the speed requirement. Standardbreds are primarily known for their racing abilities, especially in harness racing. To be registered as a Standardbred, a horse must demonstrate a certain level of speed, specifically being able to trot or pace a mile in a specified time under the rules set by breed organizations. This focus on speed is fundamental to the breed's identity, as it distinguishes Standardbreds in the competitive racing environment.

While color variety, height limits, and temperament may play roles in other breeds or be relevant to specific horse evaluations, they are not primary criteria for Standardbred registration. Instead, the emphasis on achieving specific performance metrics ensures that only those horses that meet the rigorous standards of speed can be registered, maintaining the quality and integrity of the breed.