enum {M=0, N=1, O=2} pclass;
int inhabited; /* if NZ, an index into a name array */
#define UNINHABITED -1
- int crystals; /* has crystals */
-#define MINED -1 /* used to have crystals, but they were mined out */
+ enum {mined=-1, present=0, absent=1} crystals; /* has crystals */
enum {unknown, known, shuttle_down} known;
} planet;