These are the structures im currently useing. I you figure out anything about them Please e-mail me at chrisp@halcyon.com typedef struct{ long offset; long size; char name[8]; }IWAD_ENTRY; typedef struct{ int x,y; int angle,type,options; }THING; typedef struct{ int a,b; int flags,special,tag,psdb,psdt; /*u3 seems to be linked to u2(button)*/ }LINEDEF; /*hmmmm u4 seem to be sequn unless u5 is -1*/ typedef struct{ int flags,tint; char n1[8]; char n2[8]; char n3[8]; int sec_ptr; }SIDEDEF; typedef struct{ int x,y; }VERTEX; typedef struct{ int a,b; int f,lptr; /*f always big somtimes neg*/ int flip,w; /*flip a,b one linedef w:when !0 line def ab doesnt match*/ }SEG; typedef struct{ int n,o; /*should be more to this*/ }SSECTOR; typedef struct{ int x,y; /*how big is this????*/ int a,b; int p[8]; int l,n; }NODE; typedef struct{ int fh,ch; /*floor -n- ceiling*/ char n1[8],n2[8]; /*names for tex*/ int light,special,tag; /**/ }SECTOR; typedef struct{ int a,b,c,d; /**/ }REJECT; typedef struct{ int a,b,c,d; /*something to do with texture maping(and colision??)*/ }BLOCKM;