Here is a list of which number stands for which icon.
Note: the icons here may not look like the game icons. But there are so many things which look like doors or boxes in the game that I had to make distinctions somewhere. Often an icon only "captures the spirit" of the functionality of a square. I can only hope I am not too inaccurate.
0 is a wall.
1 is an open space.
2 is a node.
3 is a walkway north.
4 is a walkway south.
5 is a walkway east.
6 is a walkway west.
7 is a door.
8 is a tube up.
9 is a tube down. 		a is a transporter(4 arrows!)
b is a box.
c is a force field.
d is a locked door.
e is a "heavy" locked door.
f is a computer terminal.
g is part of a table.
h is a bookshelf.
i is a pipe.
j is a special item. 		k is an inaccessible slide tube.
l is garbage.
m is a question mark.
n is a person.
o is a robot.
p is stairs up.
q is stairs down.
1