-int nval_del(char *xb, int xb_size, const char *name);
-int nval_set(char *xb, int xb_size, const char *name, const char *buf, int bsize, int flags);
-int nval_get(const char *xb, int xb_size, const char *name, char *buf, int bsize);
-int nval_list(const char *xb, int xb_size, char *buf, int bsize);
-int nval_load(char *xb, int xb_size, const char *src, int src_size);
-int nval_save(const char *xb, int xb_size, char *dest, int dest_size);