... Magnetospheric boundary layer is a region close to the magnetopause in which magnetosheath plasma has strong influence. ... A new boundary called the free-flow boundary has been suggested to exists between the exterior cusp and the magnetosheath (this is the boundary that is often plotted as a dashed line in schematic figures of the magnetosphere). Boundary layer is a very special region, not only because of the presence of magnetosheath plasma, but also because of the still uncertain topology. ...