struct yx_uint8 pos; /* coordinate on map */
char * fov_map; /* thing's FOV map; 'v':visible, 'H':hidden */
char * mem_map; /* map knowledge of thing by FOV and memory */
+ char * mem_depth_map; /* map of map memory up-to-dateness */
uint8_t type; /* ID of appropriate thing definition */
uint8_t lifepoints; /* 0: thing is inanimate; >0: hitpoints */
uint8_t command; /* thing's current action; 0 if none */