A “Buffer” is a surface defined by a certain distance on both sides of a line. This can be useful when data is needed around linear axes like streets or rivers.

The order extent type “Buffer” is activated by clicking on the button . Then the line of the buffer is defined in the map by clicking the respective vertices in the map with the left mouse button. Every point is represented in the map as a black square.

On the lower right of the screen, the coordinates of the points defined in the map are listed in the drop-down list.

After defining the line, the width of the buffer zone has yet to be fixed. The width in “meters” is entered in the field on the lower right :

The buffer is validated by clicking on the symbol, and drawn in red transparent colour in the map for a visual control. After having defined the order extent, the user can move on to the next step of the ordering procedure by clicking on the button .

Instead of clicking the points in the map, it is also possible to directly enter their coordinates. These coordinates are considered to refer to the actually active coordinate system:

With the button , the coordinated typed in the fields are saved in the drop-down list on the right side. The button can be used to delete the selected point from the list.

After defining the line and the width of the buffer, the buffer zone is validated with the button and drawn in red transparent colour in the map to permit a visual control. After having defined the order extent, the user can move on to the next step of the ordering procedure by clicking on the button .