- Create a new assembly
- In the "Begin assembly" Propriety Manager, click "Create layout"
- Draw an oblique line and make it and its two end points fully defined, by whatever method
- Create a plane using the "Plane" tool in the sketch toolbar, Make the plane perpendicular to the line and coincident with an end point of the line.
- Deselect anything while stay in layout mode, look at the Propriety Manager, the newly created plane is fully defined, no ( - ) before its name.
- Double click the new plane and draw a line from the endpoint of the previous line and add a "Vertical" constraint to the new line.
- Drag the free endpoint of the new line, you will see the new plane can rotate along with it.