The world consists of one area, which is regular in shape and consists of a number of cells. Each cell has a type of terrain and a number of optional data values. Each kind of per-cell data will be called a layer of the area.
Form: world
[ circumference ] properties...
This form defines the properties of the world as a whole.
Form: area
[ width [ height ] ] [ restriction ] properties...
This form defines the playing area of the world. The restriction identifies how to get data for this area from subsequent forms that are based on larger areas.