-/* Variable auxiliary data. */
-void *var_get_aux (const struct variable *);
-void *var_attach_aux (struct variable *,
- void *aux, void (*aux_dtor) (struct variable *));
-void var_clear_aux (struct variable *);
-void *var_detach_aux (struct variable *);
-void var_dtor_free (struct variable *);
-
-/* Observed categorical values. */
-struct cat_vals *var_get_obs_vals (const struct variable *);
-void var_set_obs_vals (struct variable *, struct cat_vals *);
-bool var_has_obs_vals (const struct variable *);
-
-/* Classes of variables. */
-enum dict_class
- {
- DC_ORDINARY, /* Ordinary identifier. */
- DC_SYSTEM, /* System variable. */
- DC_SCRATCH /* Scratch variable. */
- };
+/* Custom attributes. */
+struct attrset *var_get_attributes (const struct variable *);
+void var_set_attributes (struct variable *, const struct attrset *);
+bool var_has_attributes (const struct variable *);
+
+/* Encoding. */
+const char *var_get_encoding (const struct variable *);