Revision clouds are polylines that consist of sequential arcs. They are used to call attention to portions of a drawing.
A revision cloud is a polyline of sequential arcs to form a cloud-shaped object. If you review or redline drawings, you can increase your productivity by using the revision cloud feature to highlight your markups.
Create Revision Clouds
You can create a revision cloud by moving the mouse, or you can convert objects, such as a circle, ellipse, polyline, or spline, to a revision cloud. A style is available to make the cloud look as though it was drawn with a calligraphy pen. 
Modify Revision Clouds
Revision clouds offer grip-specific options depending on the grip location and the setting of the REVCLOUDGRIPS system variable.
When REVCLOUDGRIPS system variable is off, you can use the grips to edit the individual arc lengths and chords in a revision cloud. Otherwise, the grips display options to add or remove a vertex, or stretch the revision cloud or its vertex.