The tongue tip and blade are considered attached to the tongue body and move with respect to a point B nominally on the tongue-body surface. The line CB is oriented at an angle Øj+0.55pi with respect to the horizontal. Its position is expressed by polar coordinates (St, Øt) with respect to B. Active extension or retraction of the tongue tip relative to the tongue body is expressed by variations in Øt. The angle of elevation of the tongue tip has components (Øj+Øtc) reflecting the position of the jaw and the tongue body. A further component (Øtt) reflects active elevation of the tongue tip and is zero for static vowels. Again, a functional separation is made to allow tip elevation with fixed body, or involuntary tip movement due to body movement.