Section Header
    + name := CLIP;
    - comment := "Clip structure (Use for AREA).";
    - version := 1;
Section Inherit
    - parent_object:OBJECT :=
Section Public
top
/\
(x_min,y_min) X--||----------+
| |
left <= |
| |
| CLIP |
| |
| => right
| |
+----------||--X (x_max,y_max)
\/
bottom
Coord. abs clip.
    + x_min:INTEGER;
    + y_min:INTEGER;
    + x_max:INTEGER;
    + y_max:INTEGER;
    + window:AREA;
Four clip links.
    + left:CLIP;
    + right:CLIP;
    + top:CLIP;
    + bottom:CLIP;
Section Public
    - make win:AREA at (x0,y0:INTEGER) to (x1,y1:INTEGER) <-
    - create win:AREA at (x0,y0:INTEGER) to (x1,y1:INTEGER) :CLIP <-
    - set_left new_link:CLIP <-
    - set_right new_link:CLIP <-
    - set_top new_link:CLIP <-
    - set_bottom new_link:CLIP <-
    - set_x_min new:INTEGER <-
    - set_x_max new:INTEGER <-
    - set_y_min new:INTEGER <-
    - set_y_max new:INTEGER <-
    - display win:AREA <-