A work switch is an open or closed sensor. When the magnet is in front of the sensor, the sensor is closed. In Normal mode, this would be Workswitch OFF or Seeder Down. When the magnet is away from the sensor, the sensor is open. In Normal mode, this would be Workswitch ON, or Seeder Up.
If the work switch is set to inverted, the reverse is true. So when the magnet is in front of the sensor, the Workswitch is ON, or Seeder Up. When the magnet is away from the sensor, the Workswitch is OFF, or Seeder Down.