This article is from the Obedience Trials, by Cindy Tittle Moore with numerous contributions by others.
Historically, the original AKC Utility ring included a tracking
exercise that was later removed from the set of required Utility
exercises and formed the basis for today's TD test. Because of this
prior association, Tracking is considered a test of obedience, and the
TD and TDX titles are considered to be obedience titles. This is also
the reason that dogs with both UD/X and TD/X are able to combine them
into special dual titles, including UDT, etc.
 
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