In any layout design, an important issue is creating or modifying geometric elements like polygons, lines etc. in conjunction with intersections of lines, arcs or reference points like the center point of a line, the start and end point of an arc or a subdivision point. Allegro PCB Editor and OrCAD PCB Editor provide to the designer many graphical interactive functions like Add - Line, Add - Arc, Add - Circle, Add - Shape etc. and editing functions like Edit - Shape, Edit - Vertex, Edit - Move, Edit - Copy ... or placement commands.