| Inst of term * term list (* function, arguments *)
| Impl of bool * id * term * term (* strong?, label, source, target *)
-type command = Graph of id (* hierarchy graph: name *)
+type command = Require of id list (* required files: names *)
+ | Graph of id (* hierarchy graph: name *)
| Sorts of (int option * id) list (* sorts: index, name *)
| Section of id option (* section: Some id = open, None = close last *)
| Entity of kind * id * desc * term (* entity: class, name, description, contents *)
+ | Generate of term list (* predefined generated entity: arguments *)
+