-struct casewriter *sort_create_writer (struct case_ordering *, size_t value_cnt);
-struct casereader *sort_execute (struct casereader *, struct case_ordering *);
+struct casewriter *sort_create_writer (const struct subcase *,
+ const struct caseproto *);
+struct casereader *sort_execute (struct casereader *, const struct subcase *);
+struct casereader *sort_execute_1var (struct casereader *,
+ const struct variable *);