see scrCreateTileObj()

@   entrance
X   exit
0   blank (air)
1   brick
2   lush (i.e. forest or jungle decoration)
3   dark
4   push block
7   spikes
9   brick wall
.   oBlock  (moveable?)
A   altar
a   chest
B   tiki
b   oBrickSmooth
d   dice
I   golden idol
i   random item on the shop floor
K   shopkeeper
L   ladder
l   lamp
M   mattock
k   shop sign
P   ladder top
S   snake
s   (randomly) a snake or a brick
T   big ruby
W   wanted poster
w   water