.NW Level capabilities and file format

[Ter13]

I'm looking for more information on .NW levels' capabilities, and have found a distinct lack of documentation on the web.

I've heard that the .nw files allow multiple layers to be used, how is this stored in a file?

So far, I've gathered the simple file format for a one layer map.

file header:

GLEVNW01 - Don't quite understand the meaning here, possibly what version of NW the file uses?

file body:

For each horizontal row containing any modifications:

BOARD - Prefix for board data
(real) - X position of the board data (always seems to be zero. Can this change?)
(real) - Y position of the board data
(real) - Run of the board data (can this go above 64?)
(real) - Layer of the board data

(string)[run] -Contains tile data (each tile is 2 characters A-Z-a-z-(+/))

NPC - Prefix for Oldscript NPC data
(string) - Contains NPC's image file (- if no image)
(real) - NPC X position on the board
(real) - NPC Y position on the board
(string) - Contains entire NPC's script
NPCEND - Marks the end of the NPC

file footer:

File is null terminated

So far, my main questions, are:

1) OldScript NPCs are deprecated, right? How would one place new NPCs?

Obviously, Graal maps using the fourth Cartesian quaternion (I.E. 1,-1 through xINF,-xINF) however, mappings are stored as though in the first quaternion (I.E. 1,1 through xINF,xINF), which took me a second to adapt to before I could read the tile data from the file in raw form. I'm quite a bit perplexed by a few things.

Any comments or advice would be much appreciated.