diff --git a/src/cipher/cipher.ml b/src/cipher/cipher.ml
index 4d963bd8..75577d3f 100644
--- a/src/cipher/cipher.ml
+++ b/src/cipher/cipher.ml
@@ -118,8 +118,8 @@ struct
         | Some plaintext -> Some (Cstruct.to_string plaintext)
 end
 
-let secrets_variable =
-  Dream.new_local
+let secrets_field =
+  Dream.new_field
     ~name:"dream.secret"
     ~show_value:(fun _secrets -> "[redacted]")
     ()
@@ -131,19 +131,19 @@ let secrets_variable =
 let set_secret ?(old_secrets = []) secret =
   let value = secret::old_secrets in
   fun next_handler request ->
-    Dream.set_local request secrets_variable value;
+    Dream.set_field request secrets_field value;
     next_handler request
 
 let fallback_secrets =
   lazy [Random.random 32]
 
 let encryption_secret request =
-  match Dream.local request secrets_variable with
+  match Dream.field request secrets_field with
   | Some secrets -> List.hd secrets
   | None -> List.hd (Lazy.force fallback_secrets)
 
 let decryption_secrets request =
-  match Dream.local request secrets_variable with
+  match Dream.field request secrets_field with
   | Some secrets -> secrets
   | None -> Lazy.force fallback_secrets
 
diff --git a/src/dream.ml b/src/dream.ml
index 1cd455c7..0cb5be04 100644
--- a/src/dream.ml
+++ b/src/dream.ml
@@ -182,8 +182,12 @@ let with_stream message =
   set_stream message;
   message
 
+type 'a local = 'a field
+let new_local = new_field
+let local = field
+
 let with_local key value message =
-  set_local message key value;
+  set_field message key value;
   message
 
 let first message =
diff --git a/src/dream.mli b/src/dream.mli
index 27748882..cfb8101e 100644
--- a/src/dream.mli
+++ b/src/dream.mli
@@ -2349,20 +2349,40 @@ val decrypt :
 
     Dream supports user-defined per-message variables for use by middlewares. *)
 
-type 'a local
+type 'a field
 (** Per-message variable. *)
 
-val new_local : ?name:string -> ?show_value:('a -> string) -> unit -> 'a local
+(**/**)
+type 'a local = 'a field
+[@@ocaml.deprecated " Renamed to type Dream.field."]
+(**/**)
+
+val new_field : ?name:string -> ?show_value:('a -> string) -> unit -> 'a field
 (** Declares a variable of type ['a] in all messages. The variable is initially
     unset in each message. The optional [~name] and [~show_value] are used by
     {!Dream.run} [~debug] to show the variable in debug dumps. *)
 
-val local : 'b message -> 'a local -> 'a option
+(**/**)
+val new_local : ?name:string -> ?show_value:('a -> string) -> unit -> 'a field
+[@@ocaml.deprecated " Renamed to Dream.new_field."]
+(**/**)
+
+val field : 'b message -> 'a field -> 'a option
 (** Retrieves the value of the per-message variable. *)
 
-val set_local : 'b message -> 'a local -> 'a -> unit
+(**/**)
+val local : 'b message -> 'a field -> 'a option
+[@@ocaml.deprecated " Renamed to Dream.field."]
+(**/**)
+
+val set_field : 'b message -> 'a field -> 'a -> unit
 (** Sets the per-message variable to the value. *)
 
+(**/**)
+val set_field : 'b message -> 'a field -> 'a -> unit
+[@@ocaml.deprecated " Renamed to Dream.set_field."]
+(**/**)
+
 (**/**)
 val with_local : 'a local -> 'a -> 'b message -> 'b message
 [@@ocaml.deprecated
diff --git a/src/http/error_handler.ml b/src/http/error_handler.ml
index 1ec3f2f5..d1ed9611 100644
--- a/src/http/error_handler.ml
+++ b/src/http/error_handler.ml
@@ -97,7 +97,7 @@ let dump (error : Catch.error) =
     Dream.all_headers request
     |> List.iter (fun (name, value) -> p "\n%s: %s" name value);
 
-    Dream.fold_locals (fun name value first ->
+    Dream.fold_fields (fun name value first ->
       if first then
         p "\n";
       p "\n%s: %s" name value;
diff --git a/src/http/http.ml b/src/http/http.ml
index 0a88e8b1..09dd274f 100644
--- a/src/http/http.ml
+++ b/src/http/http.ml
@@ -406,7 +406,7 @@ let wrap_handler
              request_id field in requests. *)
           let user's_websocket_handler websocket =
             Lwt.with_value
-              Dream__middleware.Log.lwt_key
+              Dream__middleware.Log.id_lwt_key
               (Dream__middleware.Log.get_request_id ~request ())
               (fun () -> user's_websocket_handler websocket)
           in
diff --git a/src/middleware/flash.ml b/src/middleware/flash.ml
index 22d5e78e..17e0640c 100644
--- a/src/middleware/flash.ml
+++ b/src/middleware/flash.ml
@@ -15,8 +15,8 @@ let log =
 let five_minutes =
   5. *. 60.
 
-let storage =
-  Dream.new_local ~name:"dream.flash" ()
+let storage_field =
+  Dream.new_field ~name:"dream.flash" ()
 
 let flash_cookie =
   "dream.flash"
@@ -53,7 +53,7 @@ let flash request =
 
 let put_flash request category message =
   let outbox =
-    match Dream.local request storage with
+    match Dream.field request storage_field with
     | Some outbox -> outbox
     | None ->
       let message = "Missing flash message middleware" in
@@ -75,7 +75,7 @@ let flash_messages inner_handler request =
     else
       log ~request "%s" "No flash messages.");
   let outbox = ref [] in
-  Dream.set_local request storage outbox;
+  Dream.set_field request storage_field outbox;
   let existing = Cookie.cookie request flash_cookie in
   let%lwt response = inner_handler request in
   let entries = List.rev !outbox in
diff --git a/src/middleware/log.ml b/src/middleware/log.ml
index e7290602..f488e9ab 100644
--- a/src/middleware/log.ml
+++ b/src/middleware/log.ml
@@ -70,13 +70,13 @@ let logs_lib_tag : string Logs.Tag.def =
 
 (* Lwt sequence-associated storage key used to pass request ids for use when
    ~request is not provided. *)
-let lwt_key : string Lwt.key =
+let id_lwt_key : string Lwt.key =
   Lwt.new_key ()
 
 (* The actual request id "field" associated with each request by the logger. If
    this field is missing, the logger assigns the request a fresh id. *)
-let id =
-  Dream.new_local
+let id_field =
+  Dream.new_field
     ~name:request_id_label
     ~show_value:(fun id -> id)
     ()
@@ -86,11 +86,11 @@ let get_request_id ?request () =
   let request_id =
     match request with
     | None -> None
-    | Some request -> Dream.local request id
+    | Some request -> Dream.field request id_field
   in
   match request_id with
   | Some _ -> request_id
-  | None -> Lwt.get lwt_key
+  | None -> Lwt.get id_lwt_key
 
 (* The current state of the request id sequence. *)
 let last_id =
@@ -470,13 +470,13 @@ struct
 
     (* Get the requwst's id or assign a new one. *)
     let id =
-      match Dream.local request id with
+      match Dream.field request id_field with
       | Some id -> id
       | None ->
         last_id := !last_id + 1;
-        let new_id = string_of_int !last_id in
-        Dream.set_local request id new_id;
-        new_id
+        let id = string_of_int !last_id in
+        Dream.set_field request id_field id;
+        id
     in
 
     (* Identify the request in the log. *)
@@ -495,7 +495,7 @@ struct
     (* Call the rest of the app. *)
     Lwt.try_bind
       (fun () ->
-        Lwt.with_value lwt_key (Some id) (fun () ->
+        Lwt.with_value id_lwt_key (Some id) (fun () ->
           next_handler request))
       (fun response ->
         (* Log the elapsed time. If the response is a redirection, log the
diff --git a/src/middleware/router.ml b/src/middleware/router.ml
index e188716f..108837ea 100644
--- a/src/middleware/router.ml
+++ b/src/middleware/router.ml
@@ -165,8 +165,8 @@ let scope prefix middlewares routes =
 
 
 
-let path_variable : string list Dream.local =
-  Dream.new_local
+let path_field : string list Dream.field =
+  Dream.new_field
     ~name:"dream.path"
     ~show_value:(fun path -> String.concat "/" path)
     ()
@@ -175,24 +175,24 @@ let path_variable : string list Dream.local =
    string. *)
 (* TODO Remove this from the API. *)
 let path the_request =
-  match Dream.local the_request path_variable with
+  match Dream.field the_request path_field with
   | Some path -> path
   | None ->
     Dream.(Formats.(the_request |> target |> split_target |> fst |> from_path))
 
 (* TODO Move site_prefix into this file and remove with_path from the API. *)
 let set_path request path =
-  Dream.set_local request path_variable path
+  Dream.set_field request path_field path
 
 (* Prefix is stored backwards. *)
-let prefix_variable : string list Dream.local =
-  Dream.new_local
+let prefix_field : string list Dream.field =
+  Dream.new_field
     ~name:"dream.prefix"
     ~show_value:(fun prefix -> String.concat "/" (List.rev prefix))
     ()
 
 let internal_prefix request =
-  match Dream.local request prefix_variable with
+  match Dream.field request prefix_field with
   | Some prefix -> prefix
   | None -> []
 
@@ -200,10 +200,10 @@ let prefix request =
   Formats.make_path (List.rev (internal_prefix request))
 
 let set_prefix request prefix =
-  Dream.set_local request prefix_variable prefix
+  Dream.set_field request prefix_field prefix
 
-let params_variable : (string * string) list Dream.local =
-  Dream.new_local
+let params_field : (string * string) list Dream.field =
+  Dream.new_field
     ~name:"dream.params"
     ~show_value:(fun params ->
       params
@@ -222,7 +222,7 @@ let missing_param request name =
   failwith message
 
 let param request name =
-  match Dream.local request params_variable with
+  match Dream.field request params_field with
   | None -> missing_param request name
   | Some params ->
     try List.assoc name params
@@ -261,7 +261,7 @@ let router routes =
       match node with
       | Handler (method_, handler)
           when method_matches method_ (Dream.method_ request) ->
-        Dream.set_local request params_variable bindings;
+        Dream.set_field request params_field bindings;
         if is_wildcard then begin
           set_prefix request prefix;
           set_path request path;
@@ -279,7 +279,7 @@ let router routes =
     in
 
     let params =
-      match Dream.local request params_variable with
+      match Dream.field request params_field with
       | Some params -> params
       | None -> []
     in
diff --git a/src/middleware/server.ml b/src/middleware/server.ml
index df027256..89a4977d 100644
--- a/src/middleware/server.ml
+++ b/src/middleware/server.ml
@@ -11,8 +11,8 @@ module Stream = Dream_pure.Stream
 
 
 
-let client_variable =
-  Dream.new_local
+let client_field =
+  Dream.new_field
     ~name:"dream.client"
     ~show_value:(fun client -> client)
     ()
@@ -20,28 +20,28 @@ let client_variable =
 (* TODO What should be reported when the client address is missing? This is a
    sign of local testing. *)
 let client request =
-  match Dream.local request client_variable with
+  match Dream.field request client_field with
   | None -> "127.0.0.1:0"
   | Some client -> client
 
 let set_client request client =
-  Dream.set_local request client_variable client
+  Dream.set_field request client_field client
 
 
 
-let https_variable =
-  Dream.new_local
+let https_field =
+  Dream.new_field
     ~name:"dream.https"
     ~show_value:string_of_bool
     ()
 
 let https request =
-  match Dream.local request https_variable with
+  match Dream.field request https_field with
   | Some true -> true
   | _ -> false
 
 let set_https request https =
-  Dream.set_local request https_variable https
+  Dream.set_field request https_field https
 
 
 
diff --git a/src/middleware/session.ml b/src/middleware/session.ml
index df09c3c2..d7169597 100644
--- a/src/middleware/session.ml
+++ b/src/middleware/session.ml
@@ -19,14 +19,14 @@ type 'a back_end = {
   send : 'a -> Dream.request -> Dream.response -> Dream.response Lwt.t;
 }
 
-let middleware local back_end = fun inner_handler request ->
+let middleware field back_end = fun inner_handler request ->
   let%lwt session = back_end.load request in
-  Dream.set_local request local session;
+  Dream.set_field request field session;
   let%lwt response = inner_handler request in
   back_end.send session request response
 
-let getter local request =
-  match Dream.local request local with
+let getter field request =
+  match Dream.field request field with
   | Some session ->
     session
   | None ->
@@ -40,10 +40,10 @@ type 'a typed_middleware = {
 }
 
 let typed_middleware ?show_value () =
-  let local = Dream.new_local ~name:"dream.session" ?show_value () in
+  let field = Dream.new_field ~name:"dream.session" ?show_value () in
   {
-    middleware = middleware local;
-    getter = getter local;
+    middleware = middleware field;
+    getter = getter field;
   }
 
 
diff --git a/src/middleware/upload.ml b/src/middleware/upload.ml
index 15def736..9417c255 100644
--- a/src/middleware/upload.ml
+++ b/src/middleware/upload.ml
@@ -30,8 +30,8 @@ let initial_multipart_state () = {
 }
 
 (* TODO Dump the value of the multipart state somehow? *)
-let multipart_state_variable : multipart_state Dream.local =
-  Dream.new_local
+let multipart_state_field : multipart_state Dream.field =
+  Dream.new_field
     ~name:"dream.multipart"
     ()
 
diff --git a/src/pure/inmost.ml b/src/pure/inmost.ml
index d54aa98c..24ef3019 100644
--- a/src/pure/inmost.ml
+++ b/src/pure/inmost.ml
@@ -11,14 +11,11 @@ type status = Status.status
 type stream = Stream.stream
 type buffer = Stream.buffer
 
-module Scope_variable_metadata =
+module Custom_field_metadata =
 struct
   type 'a t = string option * ('a -> string) option
 end
-module Scope = Hmap.Make (Scope_variable_metadata)
-(* TODO Rename Scope, because there is now only one scope. *)
-(* TODO Given there are now only locals, maybe it's worth renaming them to
-   something else - there is now only one concept of variables. *)
+module Fields = Hmap.Make (Custom_field_metadata)
 
 type websocket = Stream.stream
 
@@ -30,7 +27,7 @@ and 'a message = {
   mutable headers : (string * string) list;
   mutable client_stream : Stream.stream;
   mutable server_stream : Stream.stream;
-  mutable locals : Scope.t;
+  mutable fields : Fields.t;
 }
 
 and client = {
@@ -223,29 +220,28 @@ let close_stream message =
 let is_websocket response =
   response.specific.websocket
 
-let fold_scope f initial scope =
-  Scope.fold (fun (B (key, value)) accumulator ->
-    match Scope.Key.info key with
-    | Some name, Some show_value -> f name (show_value value) accumulator
-    | _ -> accumulator)
-    scope
-    initial
 
-type 'a local = 'a Scope.key
 
-let new_local ?name ?show_value () =
-  Scope.Key.create (name, show_value)
+type 'a field = 'a Fields.key
+
+let new_field ?name ?show_value () =
+  Fields.Key.create (name, show_value)
+
+let field message key =
+  Fields.find key message.fields
 
-(* TODO Tension between "t-first" and not, because typically, for a getter, the
-   "index" parameter could be partially applied. *)
-let local message key =
-  Scope.find key message.locals
+let set_field message key value =
+  message.fields <- Fields.add key value message.fields
+
+let fold_fields f initial message =
+  Fields.fold (fun (B (key, value)) accumulator ->
+    match Fields.Key.info key with
+    | Some name, Some show_value -> f name (show_value value) accumulator
+    | _ -> accumulator)
+    message.fields
+    initial
 
-let set_local message key value =
-  message.locals <- Scope.add key value message.locals
 
-let fold_locals f initial message =
-  fold_scope f initial message.locals
 
 let request
     ?method_
@@ -275,7 +271,7 @@ let request
     headers;
     client_stream;
     server_stream;
-    locals = Scope.empty;
+    fields = Fields.empty;
   } in
 
   request
@@ -299,7 +295,7 @@ let response
     client_stream;
     server_stream;
     (* TODO This fully dead stream should be preallocated. *)
-    locals = Scope.empty;
+    fields = Fields.empty;
   } in
 
   response
diff --git a/src/pure/inmost.mli b/src/pure/inmost.mli
index 56cae5f3..d57b0b9b 100644
--- a/src/pure/inmost.mli
+++ b/src/pure/inmost.mli
@@ -111,8 +111,8 @@ val is_websocket : response -> (websocket -> unit promise) option
 
 
 
-type 'a local
-val new_local : ?name:string -> ?show_value:('a -> string) -> unit -> 'a local
-val local : 'b message -> 'a local -> 'a option
-val set_local : 'b message -> 'a local -> 'a -> unit
-val fold_locals : (string -> string -> 'a -> 'a) -> 'a -> 'b message -> 'a
+type 'a field
+val new_field : ?name:string -> ?show_value:('a -> string) -> unit -> 'a field
+val field : 'b message -> 'a field -> 'a option
+val set_field : 'b message -> 'a field -> 'a -> unit
+val fold_fields : (string -> string -> 'a -> 'a) -> 'a -> 'b message -> 'a
diff --git a/src/sql/sql.ml b/src/sql/sql.ml
index 69a667ad..af20da00 100644
--- a/src/sql/sql.ml
+++ b/src/sql/sql.ml
@@ -13,8 +13,8 @@ let log =
   Dream__middleware.Log.sub_log "dream.sql"
 
 (* TODO Debug metadata for the pools. *)
-let pool_variable : (_, Caqti_error.t) Caqti_lwt.Pool.t Dream.local =
-  Dream.new_local ()
+let pool_field : (_, Caqti_error.t) Caqti_lwt.Pool.t Dream.field =
+  Dream.new_field ()
 
 let foreign_keys_on =
   Caqti_request.exec Caqti_type.unit "PRAGMA foreign_keys = ON"
@@ -30,7 +30,7 @@ let sql_pool ?size uri =
 
   begin match !pool_cell with
   | Some pool ->
-    Dream.set_local request pool_variable pool;
+    Dream.set_field request pool_field pool;
     inner_handler request
   | None ->
     (* The correctness of this code is subtle. There is no race condition with
@@ -46,7 +46,7 @@ let sql_pool ?size uri =
     match pool with
     | Ok pool ->
       pool_cell := Some pool;
-      Dream.set_local request pool_variable pool;
+      Dream.set_field request pool_field pool;
       inner_handler request
     | Error error ->
       (* Deliberately raise an exception so that it can be communicated to any
@@ -59,7 +59,7 @@ let sql_pool ?size uri =
   end
 
 let sql request callback =
-  match Dream.local request pool_variable with
+  match Dream.field request pool_field with
   | None ->
     let message = "Dream.sql: no pool; did you apply Dream.sql_pool?" in
     log.error (fun log -> log ~request "%s" message);