-struct val_lab *val_labs_first (const struct val_labs *,
- struct val_labs_iterator **);
-struct val_lab *val_labs_first_sorted (const struct val_labs *,
- struct val_labs_iterator **);
-struct val_lab *val_labs_next (const struct val_labs *,
- struct val_labs_iterator **);
-void val_labs_done (struct val_labs_iterator **);
+/* Iterating through value labels. */
+const struct val_lab *val_labs_first (const struct val_labs *);
+const struct val_lab *val_labs_next (const struct val_labs *,
+ const struct val_lab *);
+const struct val_lab **val_labs_sorted (const struct val_labs *);