Length is the phonological correlate of durational differences between sounds, tied to the phonological concept “quantity.” The concept of length usually considers duration segmentally, attributing length to particular segments (the vowel or consonant is the locus of the property “long” or “short,” and not the syllable, foot, or word). Length being a phonological attribute, distinctions are discrete mental categories, not physical measurement, and, like most phonological attributes in generative theories, length is traditionally treated binarily.