See Also
The background of a oneline diagram can display ellipses among other items.
Edit Mode
To add a new ellipse, first go to the Draw ribbon tab and select Background > Background Ellipse from the Individual Insert ribbon group. Then position the cursor where you would like to place the upper left-hand corner of the ellipse and click with the left mouse button. An ellipse having the default size and shape is inserted. Drag the ellipse's resizing handles to resize/reshape it.
To resize or reshape an existing ellipse, click on it to select it. The resizing handles will appear, which you can then drag to reshape or resize the ellipse.
Right-click on the ellipse and choose Format Background Ellipse, or select the ellipse and use the tools in the Formatting ribbon group found on the Draw ribbon tab to change the color, line thickness and fill color of the ellipse.