Averaged rotational splitting as would be measured for a star with a two level radial rotational profile with a discontinuity at a radius α and a central to envelope rotation rate of Ω_c/Ω_e. The left-hand plot corresponds to a different central rotation rate and the right-hand plot a near surface discontinuity. The 6 per cent contours that represent the precision on the 16 Cyg A measured rotational splitting are plotted in black.