Sketch = <shape> Shape Mode *EOF*. 
Shape : 
  VisualComponent |
//  ShapeGroup |
  Box | 
  Line
  *common* "coords" <coords> Coordinates.

// Repetition-Buffer rule
ShapeGroup = "{" <shapes> List(Shape) "}".
// VisualComponents = <components> List(VisualComponent).

VisualComponent : ShapeGroup | Decorator.
Decorator : ScrollDecorator | BorderDecorator *common*
  VisualComponent.
//  VisualComponents.
ScrollDecorator = "scroll".
BorderDecorator = "border".

Coordinates = 
  <p1> Point
  <p2> Point.
Point = 
  <x> Integer
  <y> Integer.
Box = "box".
Line = "line".
Mode : Gesture | Transfer | Drag *common*
  [<next> Mode].
Gesture = "gesture" Shape <origin> Point.
Drag = "drag" <shapes> ShapeGroup <last> Point.
Transfer = "transfer" <shapes> ShapeGroup <origin> Point.
List(S) ~  {S}.

Main = .
Cursor = .
DrawingVisitor = <color> Color.
Color : Black | Red.
Black = "black".
Red = "red".