#define BT_SKY			0
#define BT_OCEAN		1
#define BT_LAKE			2
#define BT_BEACH		3
#define BT_GBEACH		4
#define BT_PLAINS		5
#define BT_HILLS		6
#define BT_EXTREMEHILLS 7
#define BT_MOUNTAINS	8
#define BT_DESERT		9
#define BT_DESERTHILLS	10
#define BT_NETHER		11

#define BTF_SNOW		0x20
#define BTF_FOREST		0x40
#define BTF_AETHER		0x80