Sub-Zone are certain surfaces on the land that fit the land shape. Road etc. You can define elements using the sub zone command.
Click the Sub-Region icon in the ribbon menu .
Next to the field toolbar, another toolbar named Route Sections will appear on the screen .
The Route Sections toolbar contains icons for drawing straight, circular and polygonal curved contours. These icons are used according to the needs while defining the sub-region.
Move the mouse over the terrain you defined earlier.
Click on the corners of the sub-region element in the drawing screen.
When you define the contour and reach the point where you started, the process will be completed.