diff --git a/ocaml/typing/env.ml b/ocaml/typing/env.ml
index 69c9b9247ce..536f9131c1e 100644
--- a/ocaml/typing/env.ml
+++ b/ocaml/typing/env.ml
@@ -877,12 +877,15 @@ let md md_type =
 
 (** The caller is not interested in modes, and thus [val_modalities] is
 invalidated. *)
+(* CR zqian: this is not needed *)
 let vda_description vda =
   let vda_description = vda.vda_description in
   {vda_description with val_modalities = Mode.Modality.Value.undefined}
 
 (** The caller wants the mode of the [value_data] *)
+(* CR zqian: call this [normalize_vda_mode] *)
 let apply_val_modalities vda =
+  (* CR zqian: either inline this, or move to [types.ml] *)
   let decouple_val_modalities (vd : Subst.Lazy.value_description) =
     let modalities = vd.val_modalities in
     let vd = {vd with val_modalities = Mode.Modality.Value.id |> Mode.Modality.Value.internalize} in
@@ -1295,6 +1298,8 @@ let find_cltype path env =
       (NameMap.find s sc.comp_cltypes).cltda_declaration
   | Papply _ | Pextra_ty _ -> raise Not_found
 
+(* Have two versions, one takes path, one takes identity. The first doesn't run
+   locks, the second does. *)
 let find_value path env =
   let data, locks = find_value_full path env in
   let data = apply_val_modalities data in
@@ -1823,6 +1828,7 @@ let rec components_of_module_maker
         Lazy_backtrack.create addr
       in
       (* structures are always legacy *)
+      (* CR zqian: rename this to [module_mode] *)
       let mmode = Mode.Value.legacy |> Mode.Value.disallow_right in
       List.iter (fun ((item : Subst.Lazy.signature_item), path) ->
         match item with
@@ -3429,6 +3435,7 @@ let lookup_value ~errors ~use ~loc lid env =
   let path, locks, vda =
     lookup_value_lazy ~errors ~use ~loc lid env
   in
+  (* CR zqian: add comments about the ordering the applying modality and walk_locks *)
   let vda = apply_val_modalities vda in
   let vd = Subst.Lazy.force_value_description vda.vda_description in
   let vmode =
@@ -3774,6 +3781,7 @@ let fold_modules f lid env acc =
           acc
       end
 
+(* CR zqian: also passes mode in additional vda_description *)
 let fold_values f =
   find_all wrap_value (fun env -> env.values) (fun sc -> sc.comp_values)
     (fun k p ve acc ->
diff --git a/ocaml/typing/mode_intf.mli b/ocaml/typing/mode_intf.mli
index 800b69b2be3..817928d0955 100644
--- a/ocaml/typing/mode_intf.mli
+++ b/ocaml/typing/mode_intf.mli
@@ -447,6 +447,7 @@ module type S = sig
   val value_to_alloc_r2g : ('l * 'r) Value.t -> ('l * 'r) Alloc.t
 
   module Modality : sig
+    (* CR zqian: have [const] and [var], and an injection from [const] to [var]. *)
     type _user = private User
 
     type _internal = private Internal
@@ -498,6 +499,7 @@ module type S = sig
       val apply_left : 'd t -> (allowed * 'r) Value.t -> Value.l
 
       (** [cons m t] returns the modality that is [m] after [t]. *)
+      (* CR zqian: call this [compose]. *)
       val cons : atom -> user -> user
 
       (** [singleton m] returns the modality containing only [m]. *)
@@ -505,6 +507,7 @@ module type S = sig
 
       (** Returns the list of [atom] in the given modality. The list is
           commutative. *)
+      (* CR zqian: return record, then we don't need [Exist.t]. *)
       val to_list : user -> atom list
 
       type error =
@@ -528,6 +531,7 @@ module type S = sig
       (** Printing for debugging. *)
       val print : Format.formatter -> 'd t -> unit
 
+      (* CR zqian: consider spliting the [lr]. Also, label the arguments. *)
       val infer : Value.lr -> Value.l -> internal
 
       (** Returns a user modality weaker than the given modality. The returned
@@ -544,6 +548,7 @@ module type S = sig
 
       (** Returns a user modality by asserting the given modality is already
       user modality and returning it. *)
+      (* CR zqian: rename to [to_const_exn]. *)
       val zap_assert : 'd t -> user
 
       (** The top modality; [sub x max] succeeds for any [x]. *)
diff --git a/ocaml/typing/typemod.ml b/ocaml/typing/typemod.ml
index aae7179e92f..d0bfb7ef943 100644
--- a/ocaml/typing/typemod.ml
+++ b/ocaml/typing/typemod.ml
@@ -2875,6 +2875,7 @@ and type_structure ?(toplevel = None) funct_body anchor env sstr =
               let vd, mode =  Env.find_value (Pident id) newenv in
               let vd = Subst.Lazy.force_value_description vd in
               (* structures are always legacy *)
+              (* CR zqian: rename this to [module_mode] *)
               let mmode = Mode.Value.legacy in
               begin match Mode.Value.Comonadic.submode
                 mode.Mode.comonadic