The foregoing analysis assumes that the length L of the conductor is much greater than its width W, so edge channels are the only states at the Fermi level that extend from source to drain. If L ≪ W, additional extended states may appear in the bulk of the 2DEG, whenever the Fermi level lies in a bulk Landau level. An experiment by Fang et al. in this short-channel regime, to which our analysis does not apply, is discussed by B¨uttiker.386