The error table contains negative numbers because these sensors act as Hall Effect devices when a magnetic field is applied. The sensor voltage increases, resulting in a reduced equivalent temperature since the sensor is a negative temperature coefficient device. At low temperatures and high magnetic fields, the voltage increases so much that it exceeds the maximum standard voltage that the diode would normally produce.
Parallel in the case of the SD package means that the field is in the same plane as the leads. Perpendicular means it is at a right-angle to the leads, running from the mounting base of the sensor, through the face.
For the CU bobbin, this becomes more difficult to explain because the SD package is embedded inside the CU bobbin. Let me know if you really need to know the orientation of the sensor element inside the CU bobbin.