# Forming Polylines

Polylines are formed using the mouse in the Polyline cursor mode .

In the Polyline cursor mode the functionality of the mouse is as follows.

Clicking when the grid is drawn adds a point to the polyline at that position on the grid.
Clicking when the grid is not drawn adds a point to the polyline at that position on the picture plane; i.e. on the plane normal to the line of sight through the object point.
Clicking on a node adds a point to the polyline at the position of the node. If the node is not in the plane of the current grid the option is given to change the current grid to one at the elevation of the node. If the current grid is changed then the polyline is displayed in the new current grid plane; otherwise the new point is positioned at the projected position of the node on the current grid plane.
Dragging an existing point changes the position of that point to the grid position dragged to.

The following commands are also available on the right-click menu when in the Polyline cursor mode.

And on the main menu:

Edit | Select String – This extends the polyline forward from the last polyline segment, adding vertices at the positions of closest aligned displayed nodes or grid points. The straightness tolerance preference is used to determine whether a node or grid point is aligned, allowing this command to be used to select curved polylines.