VpClip

Select viewport to clip

Chooses the viewport to clip: in a layout tab:

• Click on the border of a single viewport.
• Clipped viewports can be reclipped. 
• Use the Delete option to remove clipping.

Select clipping entity

Converts a closed entity, such as a circle or closed polyline. into a viewport boundary. The entity must have be drawn in paper space.

Polygonal

Draws a polygonal viewport border made of straight and arc segments; prompts you:

1. Specify start point - (pick the first point of the polyline.)

2. Set next point or [draw Arcs/Distance] - (pick another point, or choose an option.)

3. Set next point or [draw Arcs/Distance/Follow/Undo] - (pick another, point or choose an option.)

4. Set next point or [draw Arcs/Close/Distance/Follow/Undo] - (enter an option:)

• Pick another point
• Choose an option
• Press Enter to  close the polygon automatically

Polygonal viewports must have at least three vertices. 

Polygonal | draw Arcs

Draws an arc segment in the polygonal viewport; prompts you:

Set end of arc or [draw Lines/ Angle/ CEnter/ CLose/ Direction/ Radius/ Second point/Undo] - (Pick a point or enter an option;) see the Arc command for the meaning of the options

Polygonal | Distance

Specifies the distance and angle for the next polygonal segment; prompts you:

1. Distance for segment - (enter a distance, or show the distance by picking a point.)

2. Angle of segment - (enter an angle, or show the angle by picking a point.)

Polygonal | Follow

Draws the next segment at the same angle as the previous polygonal segment; prompts you:

Length of line - (specifies the length of the segment.)

Polygonal | Undo

Undoes the last polygonal segment.

Polygonal | Close

Closes the polygon, and then displays the model space drawing.

Polygonal | Delete

Deletes the clipping boundary, and returns the original rectangular viewport. (This option appears only when you select a clipped viewport.)