Sketch an ellipse by selecting its center point and a radius in 2 directions.
For example, click Annotate tab Detail panel
Detail panel
 (Detail Line).
 (Detail Line). 
 Draw panel
Draw panel
 (Ellipse) or
 (Ellipse) or  (Pick Lines).
 (Pick Lines). When you create a full ellipse with an offset, the result is a spline.
For example, if you create a mass element as a full ellipse with an offset and then attempt to create a wall on the face of the mass element, the ellipse is not considered contiguous, as shown in the following image.

Snapping is enabled for the ellipse, and a preview ellipse displays.
An editable listening dimension displays the radius of the major axis.

An editable listening dimension displays the radius of the minor axis.
