Obligatory contour principle

The obligatory contour principle (frequently abbreviated OCP) is a hypothesis in autosegmental phonology that states that (certain) consecutive identical features are banned in underlying representations. The OCP is most frequently cited when discussing the tones of tonal languages (stating for example that the same morpheme may not have two underlying high tones), but it has also been applied to other aspects of phonology. The principle is part of the larger notion of horror aequi, that language users generally avoid repetition of identical linguistic structures.