Applies a constraint to draw orthogonal lines to the map axis
While working with one of the applicable Create Geometry tools, the Ortho Mode applies a constraint over the allowable location of the vertexes, that will allow to set a vertex only over one of the orthogonal lines relative to the last vertex in the currently being edited geometry.
Press the _Ortho Mode_ button on the Modes Toolbar at any time while creating a LineString or a Polygon.
As shown in Figure 1, once you activate the Ortho Mode, a pair of orthogonal axes will be shown to indicate the allowable directions of the line segment to be added.
Figure 1 Ortho Mode activated
You can keep adding vertexes both in horizontal or vertical direction while Ortho Mode is active, as shown in Figure 2.
Figure 2 Adding more vertexes in Ortho mode
To get out of Ortho Mode, just select another mode or deactivate the button.