If you’re using a custom image as the base layer, you can use this field (in conjunction with Left-most Coordinate, Bottom-most Coordinate, and Right-most Coordinate) to align your image with specific coordinates, so the nodes are displayed in your intended locations.

Enter a latitude in DD (decimal degrees) notation that coincides with the top border of the image. The default value is 85, which will place the top border of the image on the 85th parallel north.