The file begins with the four-byte magic number 72371524, and then two four-byte offsets to the polygon and thing records, in that order.

Then there follow records of the following format for polygons, until the offset specified for things:

int			tex_type_id		; 0 for flat, 1 for tex
int			vx_order		; 0 if floor, 1 if ceil, 2 for both
						; planes, 3 for clockwise vertices
char[8]			tex_name		; flat or texture name, null-padded
int			num_vertices		; number of vertices in polygon
num_vertices many:
	float	x				; Vertex co-ordinate.
	float	y				; "
	float	z				; "
	float	u				; Texture domain co-ordinate.
	float	v				; "

Finally there are the thing records, thus:

int	type	; Class of thing
int	angle	; Anticlockwise angle from 0-359, 0 being +ve x dir
int	x	; Position
int	y	; "
int	z	; "