char cHeader[12];
char cVersion[8];       // file version
short iSquaresX;        // number of squares X
short iSquaresY;        // number of squares Y
int iGroups;            // total number of groups
int iOffsets[32];       // level data start offsets ("number of levels" times)
lev Level[32];          // level data ("number of levels" times)
   
typedef struct sqr {
   short iTEast;        // textures
   short iTWest;
   short iTNorth;
   short iTSouth;
   short iTFloor;
   short iTCeiling;
   short iMapped;       // 0 = not mapped, 3 = fully mapped
   short iGroup;        // group associated with the square
   bool bRock;          // is square rock?
} sqr;

typedef struct lev {
   char cUnknown[8];
   short iSquaresX;     // number of squares X
   short iSquaresY;     // number of squares Y
   short iLevel;        // level number
   short iGroups;       // total number of groups on level
   char cUnknown2[170];
   sqr Square[2025];    // change to dynamic!
} lev;   

typedef struct grp {
   int iTypes;          // types of monsters that can spawn in group
   short iGID;          // GID (unknown, is set to 0)
   short iLairFreq;     // always, usually, rarely, never
   short iLairMonster;  // laired monster ID
   short iGroupFreq;    // ?? always, usually, rarely, never
   short iSpecMod;      // id = extinguish, water, quicksand, rotator...
   short iModValue;     // if SpecMod needs a value, it's entered here
   short iToughness;    // toughness = level
   short iRegen;        // is set to 0
   short iSound;        // group ambient sound ID
   char cUnknown[13];      
   short iSquares;      // total number of squares in group
} grp;

CPtrArray pGrpData;     // iGroups times the grp structure