World Description Format

Chunk based (like 3DS)

Types

(u)char  1 byte
(u)short 2 bytes
(u)int   4 bytes
float    4 bytes
string   n bytes (NULL terminated)

Chunk structure

short ChunkId
uint  NextChunk (or NULL)
...   Chunk data

Chunk Hierarchy

Difference with 3DS: Every chunk list in the hierarchy is NULL terminated, this indicates the reading software should continue reading the previous level in the hierarchy. 
WDF
+--Description
+--Name
+--Object(*)
|  |
|  ...
|  +--PolygonalModel
|  |  +--Name
|  |  +--Mesh
|  |  |  +--VertexList
|  |  |  +--FaceList
|  |  +--Mesh
|  |     +--VertexList
|  |     +--FaceList
...

Chunk Description

WDF

ushort version

Description

string

Name

string

Object

Polymorphic, can be:

PolygonalModel

list of Meshes

Mesh

VertexList