Construction Ellipse Based on Copy of Graphic Line

The Ellipse command allows creation of construction ellipses based on graphic lines (ellipses or elliptical arcs), only if such graphic lines are the associative copies of other graphic lines. Associative copies are created using copying and array creation commands in the associative mode.  

In order to create a construction ellipse based on such line, using object snappings, move the cursor over it and press or <Enter>. In result, a construction ellipse coinciding with the selected graphic line will be created.

However, you can create construction ellipses based on graphic lines, which are not associative copies, in the same manner, using the Line command, as well as using the connected drawing mode of Node and Graphic Line commands.