quality:correction, linguistic:translation
Front, raised and retracted

The conception of the tongue moving in two directions, high – low and front – back, is not supported by articulatory evidence and does not clarify how articulation affects vowel quality. Vowels may instead be characterized by the three directions of movement of the tongue from its neutral position: front (forward), raised (upward and back), and retracted (downward and back). Front vowels (and, to a lesser extent, etc.), can be secondarily qualified as close or open, as in the traditional conception, but this refers to jaw rather than tongue position. In addition, rather than there being a unitary category of back vowels, the regrouping posits raised vowels, where the body of the tongue approaches the velum (, etc.), and retracted vowels, where the root of the tongue approaches the pharynx (, etc.):

Membership in these categories is scalar, with the mid-central vowels being marginal to any category.