USDF
excerpts from USDF 2015 Glossary of Judging Terms
Behind The Bit
An evasion in which the horse retracts or shrinks back from the bit/contact. The head may or may not be behind the vertical.
Behind The Vertical
With the horse’s face viewed in profile, the front of the horse’s nose falls behind a vertical line dropped from the top of its forehead. The horse may or may not be behind the bit.
Elevation
Raised position of the forehand (head, neck, and ribcage). The neck is elevated from its base with the poll as the highest point and the face slightly in front of the vertical.
Hyperflexion (Rollkur)
Exaggerated flexion of the horse’s neck, with a low poll and the face far behind the vertical. There is a spectrum from humanely riding the horse behind the vertical to forcefully or aggressively riding the horse in a hyperflexed position and /or sustaining the hyperflexion for more than a few minutes. There may be a gray area between the acceptable and the abusive that is a matter of judgment.
Obedience
Submission in reference to the accurate performance of the required exercise,in contrast to submission in regard to the basics. The horse may demonstrate resistance or evasion (lack of submission in the basics), yet still be “obedient.” For example, if the horse performs a series of flying changes without mistakes and in the correct place but is behind the vertical, tilting his head and swishing his tail, he performs the exercise obediently, but is not submissive in regard to the basics.
On The Bit
Acceptance of contact (without resistance or evasion) with a stretched topline and with lateral and longitudinal flexion as required. The horse’s face line is, as a rule, slightly in front of the vertical.
Overflexed
Behind the vertical, due to excessive longitudinal flexion at the poll and/or upper joints of the neck.