GGU-3D-SSFLOW: "(Potentials) In section" menu item
After selecting this menu item several FEM nodes can be simultaneously assigned a potential boundary condition in a defined section, or an existing boundary condition be deleted. For this click four points in an anti-clockwise direction using the left mouse button. The right mouse button will undo. The definition refers to all nodes within the quadrilateral.

You can now define the potentials or delete all marked potentials. The definition applies to the nodes located within the section. In addition, by pressing "All to elevation head", it is possible to define the potentials in the enclosing polygon as being at the elevation head entered for the system. If the "Apply to all" check box is activated the boundary condition at the marked points are adopted for all planes.