The Temperature, parting plane (bottom) result shows the average temperature of the parting plane on the side of the parting plane element that is designated as bottom.
Parting planes are used to define the interface conductance between two pieces of the mold that are composed of the same material. There should be a small variation in temperature across the bottom and top faces of the parting plane and between the top and bottom faces. The greater the difference, the more influence the interface conductance has on the cooling of the part, which may contribute to the part being poorly cooled.