#define STATE_FOUND 0 // After discovered, before messed with
#define STATE_IN_CAVITY 1 // State value common to all gemstones
+/* Special fixed object-state values - integers > 0 are location */
+#define IS_FIXED -1
+#define IS_FREE 0
+
/* Map a state property value to a negative range, where the object cannot be
* picked up but the value can be recovered later. Avoid colliding with -1,
* which has its own meaning. */