Every plane is characterized by the number of units in x and y direction. The unit type of a plane can be defined and changed by . The position of the planes is determined relative to the previous plane. The upper left corner of plane no. 1 is always positioned at the coordinates .
Every plane is associated with a plane number.
This number is introduced to address the planes in a clear way. The number is important for the link editor. The user cannot change this number. It has been implemented for future use with the 3D visualization component.