[Thought]

Found it.

The new level format is text based. Use a text editor which doesn't wrap lines.
It begins with the signature GLEVNW01.
It can contain following data types:

- board lines:

BOARD x y width layerindex <tilesdata>

This is one line of the background layer. 'tilesdata' has a length if w*2
characters; each tile is a 12bit-index into the tile list (pics1.gif) and is
encoded in two base64 characters (upper 6 bit first)
base64: String = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvw xyz0123456789+/'
so AA is tile 0, AB is tile 1, AC is tile 2, // is tile 4095 (=0xFFF)

- level links:

LINK <destination-level> x y width height newx newy

The link attributes are the same like in the link options window in Graal.
destination-level, newx and newy must not contain spaces.

- signs:

SIGN x y
text
...
SIGNEND

Signs may be empty, but SIGNEND must always be there.

- npcs:

NPC imagefilename x y
script
...
NPCEND

If the npc doesn't have a filename (invisible npc), then write '-' for imagefilename.
x and y may be floating point values. The npc script may be empty, but NPCEND
must always be there

- baddies:

BADDY x y type
attackverse
hurtverse
winverse
BADDYEND

'type' is the baddy name (graysoldier ... dragon ) or index (0...9). You don't need
to write all 3 verses, it's also possible to only write attackverse+hurtverse or only
attackverse, but BADDYEND must always be there.

- chests:

CHEST x y item signindex

item is the item name (greenrupee ... spinattack) or item index (0...24)