#line_of_force__field_line__fieldline  an imaginary line in a field of force; direction of the line at any point is the direction of the force at that point
  supertype:  #line.location  a spatial location defined by a real or imaginary unidimensional extent
  subtype:  #electrical_line_of_force  a line of force in an electrical field
  subtype:  #magnetic_line_of_force  a line of force in a magnetic field

No statement uses or specializes #line_of_force; click here to add one.