A Far Back is a structure in the distance. You find it in the Back category of the creator. You can use several large cells, and the points of a polygon:

-300 70
-250 30
-220 40
-200 30
-180 50
-150 -20 CELL 3
-100 0
0 0 1
100 0

// more
120 40
130 60
150 50 CELL 2
200 80

Each line consists of the x and y coordinate forming the Far Back's upper polygon line, plus an optional CELL keyword with a number indicating the cell you want to show there (like a glossy mountaintop, trees, huts and anything you can imagine). The double slash "//" indicates a comment, and newlines can be used freely.

To display a cell at a slightly different position than the polygon's point, you can use an offset like this:

...
50 50 CELL 1 -10 20
...

You can also fully disconnect it from the polygon like this:

...
CELL 1 -50 30
...

The first color used in your Far Back's palette during creation is the color the polygon will use, too. You can use up to 100 coordinates, each with values from -500 to 500 (-300 to 300 for cell coordinates), and display images up to 30 times.

To rotate a cell, use the word "rotate" (at any position in the line) followed by a number from -360 to 360:

...
50 50 CELL 1 ROTATE 180
...

Use the word "mirror" anywhere to mirror the cell horizontally, and "flip" to mirror it vertically:

...
50 50 CELL 1 FLIP
70 70 CELL 2 MIRROR
...