Object Snap or OSNAP improves our working efficiency by providing a way to specify precise locations on objects such as midpoint, endpoint and center.

Then how about Quadrant, an option not frequently used?

Quadrant snaps to quadrant point of an arc, circle, ellipse, or elliptical arc.

How to specify Quadrant object snap mode?

Enter OSNAP and press Enter key to pop up the Drafting Settings dialog box,

Check the box before Quadrant and click OK.

Take an ellipse as an example, draw a random ellipse, as shown in the following picture,

Since the object snap prompts for a point within a command, we need to execute a command such as LINE command, when we are prompted to specify first point, we can move our cursor along the circumference and we will see the marker indicating quadrant points,