The coronal magnetic models of Altschuler and Newkirk (1969), Schatten, Wilcox and Ness (1969), and Schatten (1971) that allowed calculations of the coronal magnetic field from the observed photospheric magnetic field shed light on the origin of sectors. Figure 1 from Schatten's (1971) “Current Sheet Model” is a schematic representation of these similar models. There are three distinct regions in these models where different physical phenomena occur. The photosphere, where the magnetic fields are governed by the detailed motions and currents in the plasma is considered a boundary condition for the model. Above the photosphere, the plasma density diminishes very rapidly with only moderate decreases in the magnetic energy density. This results in the middle region where the magnetic energy density is greater than plasma energy density and hence controls the configuration. One may then utilize the force-free condition, j × B = 0, and in fact make the more restrictive assumption that this region is current free. The magnetic field in this region can be derived from a solution to the Laplace equation.