It's possible to define some user defined regions in space for particular refinement.
They have to be declared in geometry dictionary (after the STL and its patches) and there is a dedicated dictionary in castellated dictionary to set the required refinement level.
It defines a box in the space by bounding points.
It defines a sphere in the space by center and radius.
It defines a cylinder in the space by height vector and radius.
It defines a plate in the space by origin and span. It has no thickness and can be used only with distance mode
span (1 2 0); // One dimension must be 0 (has no thickness)
It defines a plane in the space by point and normal vector. <Can be used only in distance mode.>
basePoint (0 0 0);
It defines a plane in the space by three points. <Can be used only in distance mode.>
point1 (0 0 0);