-bool mv_is_resizable (const struct missing_values *, int width);
-void mv_resize (struct missing_values *, int width);
-
-typedef bool mv_is_missing_func (const struct missing_values *,
- const union value *);
-
-/* Is a value system or user missing? */
-bool mv_is_value_missing (const struct missing_values *, const union value *);
-bool mv_is_num_missing (const struct missing_values *, double);
-bool mv_is_str_missing (const struct missing_values *, const char[]);
-
-/* Is a value user missing? */
-bool mv_is_value_user_missing (const struct missing_values *,
- const union value *);
-bool mv_is_num_user_missing (const struct missing_values *, double);
-bool mv_is_str_user_missing (const struct missing_values *, const char[]);
+/* Adding and modifying discrete values. */
+bool mv_add_value (struct missing_values *, const union value *);
+bool mv_add_str (struct missing_values *, const uint8_t[]);
+bool mv_add_num (struct missing_values *, double);
+void mv_pop_value (struct missing_values *, union value *);
+bool mv_replace_value (struct missing_values *, const union value *, int idx);