Compose/Decompose – In this example there are hundreds of lines and arcs. They could be grouped together, but that would not allow you to color the inside of the object. Composing all of these objects into a single polyline will allow you to do structural calculations on the cross-section, color the inside of the object, find its area, or extrude it. Decompose is the opposite. It takes a complex object and breaks it down into its components.