diff --git a/src/proto_alpha/lib_protocol/src/alpha_context.mli b/src/proto_alpha/lib_protocol/src/alpha_context.mli
index a9bfac038..6a06951f0 100644
--- a/src/proto_alpha/lib_protocol/src/alpha_context.mli
+++ b/src/proto_alpha/lib_protocol/src/alpha_context.mli
@@ -79,7 +79,7 @@ module Raw_level : sig
 
   include BASIC_DATA
   type raw_level = t
-  val arg: raw_level RPC_arg.arg
+  val rpc_arg: raw_level RPC_arg.arg
 
   val diff: raw_level -> raw_level -> int32
 
@@ -95,7 +95,7 @@ module Cycle : sig
 
   include BASIC_DATA
   type cycle = t
-  val arg: cycle RPC_arg.arg
+  val rpc_arg: cycle RPC_arg.arg
 
   val root: cycle
   val succ: cycle -> cycle
@@ -375,7 +375,7 @@ module Voting_period : sig
 
   include BASIC_DATA
   type voting_period = t
-  val arg: voting_period RPC_arg.arg
+  val rpc_arg: voting_period RPC_arg.arg
 
   val root: voting_period
   val succ: voting_period -> voting_period
@@ -485,7 +485,7 @@ module Contract : sig
 
   include BASIC_DATA
   type contract = t
-  val arg: contract RPC_arg.arg
+  val rpc_arg: contract RPC_arg.arg
 
   val to_b58check: contract -> string
   val of_b58check: string -> contract tzresult
diff --git a/src/proto_alpha/lib_protocol/src/alpha_services.ml b/src/proto_alpha/lib_protocol/src/alpha_services.ml
index da4b62605..8c3d07ac4 100644
--- a/src/proto_alpha/lib_protocol/src/alpha_services.ml
+++ b/src/proto_alpha/lib_protocol/src/alpha_services.ml
@@ -42,7 +42,7 @@ module Nonce = struct
         ~description: "Info about the nonce of a previous block."
         ~query: RPC_query.empty
         ~output: info_encoding
-        RPC_path.(custom_root / "context" / "nonces" /: Raw_level.arg)
+        RPC_path.(custom_root / "context" / "nonces" /: Raw_level.rpc_arg)
 
   end
 
diff --git a/src/proto_alpha/lib_protocol/src/blinded_public_key_hash.mli b/src/proto_alpha/lib_protocol/src/blinded_public_key_hash.mli
index 7e7da12cf..e5a8ac417 100644
--- a/src/proto_alpha/lib_protocol/src/blinded_public_key_hash.mli
+++ b/src/proto_alpha/lib_protocol/src/blinded_public_key_hash.mli
@@ -9,6 +9,9 @@
 
 include S.HASH
 
+val encoding : t Data_encoding.t
+val rpc_arg : t RPC_arg.t
+
 type activation_code
 val activation_code_encoding : activation_code Data_encoding.t
 
diff --git a/src/proto_alpha/lib_protocol/src/contract_repr.ml b/src/proto_alpha/lib_protocol/src/contract_repr.ml
index 0f56f6aee..58b67e18f 100644
--- a/src/proto_alpha/lib_protocol/src/contract_repr.ml
+++ b/src/proto_alpha/lib_protocol/src/contract_repr.ml
@@ -135,7 +135,7 @@ let incr_origination_nonce nonce =
   let origination_index = Int32.succ nonce.origination_index in
   { nonce with origination_index }
 
-let arg =
+let rpc_arg =
   let construct = to_b58check in
   let destruct hash =
     match of_b58check hash with
diff --git a/src/proto_alpha/lib_protocol/src/contract_repr.mli b/src/proto_alpha/lib_protocol/src/contract_repr.mli
index 8c124a0c3..b98faf464 100644
--- a/src/proto_alpha/lib_protocol/src/contract_repr.mli
+++ b/src/proto_alpha/lib_protocol/src/contract_repr.mli
@@ -58,7 +58,7 @@ val encoding : contract Data_encoding.t
 
 val origination_nonce_encoding : origination_nonce Data_encoding.t
 
-val arg : contract RPC_arg.arg
+val rpc_arg : contract RPC_arg.arg
 
 module Index : sig
   type t = contract
diff --git a/src/proto_alpha/lib_protocol/src/contract_services.ml b/src/proto_alpha/lib_protocol/src/contract_services.ml
index 990f56494..786b49abf 100644
--- a/src/proto_alpha/lib_protocol/src/contract_services.ml
+++ b/src/proto_alpha/lib_protocol/src/contract_services.ml
@@ -51,14 +51,14 @@ module S = struct
       ~description: "Access the balance of a contract."
       ~query: RPC_query.empty
       ~output: Tez.encoding
-      RPC_path.(custom_root /: Contract.arg / "balance")
+      RPC_path.(custom_root /: Contract.rpc_arg / "balance")
 
   let manager =
     RPC_service.get_service
       ~description: "Access the manager of a contract."
       ~query: RPC_query.empty
       ~output: Signature.Public_key_hash.encoding
-      RPC_path.(custom_root /: Contract.arg / "manager")
+      RPC_path.(custom_root /: Contract.rpc_arg / "manager")
 
   let manager_key =
     RPC_service.get_service
@@ -67,56 +67,56 @@ module S = struct
       ~output: (obj2
                   (req "manager" Signature.Public_key_hash.encoding)
                   (opt "key" Signature.Public_key.encoding))
-      RPC_path.(custom_root /: Contract.arg / "manager_key")
+      RPC_path.(custom_root /: Contract.rpc_arg / "manager_key")
 
   let delegate =
     RPC_service.get_service
       ~description: "Access the delegate of a contract, if any."
       ~query: RPC_query.empty
       ~output: Signature.Public_key_hash.encoding
-      RPC_path.(custom_root /: Contract.arg / "delegate")
+      RPC_path.(custom_root /: Contract.rpc_arg / "delegate")
 
   let counter =
     RPC_service.get_service
       ~description: "Access the counter of a contract, if any."
       ~query: RPC_query.empty
       ~output: int32
-      RPC_path.(custom_root /: Contract.arg / "counter")
+      RPC_path.(custom_root /: Contract.rpc_arg / "counter")
 
   let spendable =
     RPC_service.get_service
       ~description: "Tells if the contract tokens can be spent by the manager."
       ~query: RPC_query.empty
       ~output: bool
-      RPC_path.(custom_root /: Contract.arg / "spendable")
+      RPC_path.(custom_root /: Contract.rpc_arg / "spendable")
 
   let delegatable =
     RPC_service.get_service
       ~description: "Tells if the contract delegate can be changed."
       ~query: RPC_query.empty
       ~output: bool
-      RPC_path.(custom_root /: Contract.arg / "delegatable")
+      RPC_path.(custom_root /: Contract.rpc_arg / "delegatable")
 
   let script =
     RPC_service.get_service
       ~description: "Access the code and data of the contract."
       ~query: RPC_query.empty
       ~output: Script.encoding
-      RPC_path.(custom_root /: Contract.arg / "script")
+      RPC_path.(custom_root /: Contract.rpc_arg / "script")
 
   let storage =
     RPC_service.get_service
       ~description: "Access the data of the contract."
       ~query: RPC_query.empty
       ~output: Script.expr_encoding
-      RPC_path.(custom_root /: Contract.arg / "storage")
+      RPC_path.(custom_root /: Contract.rpc_arg / "storage")
 
   let info =
     RPC_service.get_service
       ~description: "Access the complete status of a contract."
       ~query: RPC_query.empty
       ~output: info_encoding
-      RPC_path.(custom_root /: Contract.arg)
+      RPC_path.(custom_root /: Contract.rpc_arg)
 
   let list =
     RPC_service.get_service
diff --git a/src/proto_alpha/lib_protocol/src/cycle_repr.ml b/src/proto_alpha/lib_protocol/src/cycle_repr.ml
index d6179d538..b8297513e 100644
--- a/src/proto_alpha/lib_protocol/src/cycle_repr.ml
+++ b/src/proto_alpha/lib_protocol/src/cycle_repr.ml
@@ -11,7 +11,7 @@ type t = int32
 type cycle = t
 
 let encoding = Data_encoding.int32
-let arg =
+let rpc_arg =
   let construct = Int32.to_string in
   let destruct str =
     match Int32.of_string str with
diff --git a/src/proto_alpha/lib_protocol/src/cycle_repr.mli b/src/proto_alpha/lib_protocol/src/cycle_repr.mli
index 3e4308d4f..194c920cb 100644
--- a/src/proto_alpha/lib_protocol/src/cycle_repr.mli
+++ b/src/proto_alpha/lib_protocol/src/cycle_repr.mli
@@ -11,7 +11,7 @@ type t
 type cycle = t
 include Compare.S with type t := t
 val encoding: cycle Data_encoding.t
-val arg: cycle RPC_arg.arg
+val rpc_arg: cycle RPC_arg.arg
 val pp: Format.formatter -> cycle -> unit
 
 val root: cycle
diff --git a/src/proto_alpha/lib_protocol/src/delegate_services.ml b/src/proto_alpha/lib_protocol/src/delegate_services.ml
index 3502a6e78..93cfed80d 100644
--- a/src/proto_alpha/lib_protocol/src/delegate_services.ml
+++ b/src/proto_alpha/lib_protocol/src/delegate_services.ml
@@ -314,8 +314,8 @@ module Baking_rights = struct
       let open RPC_query in
       query (fun levels cycles delegates max_priority all ->
           { levels ; cycles ; delegates ; max_priority ; all })
-      |+ multi_field "level" Raw_level.arg (fun t -> t.levels)
-      |+ multi_field "cycle" Cycle.arg (fun t -> t.cycles)
+      |+ multi_field "level" Raw_level.rpc_arg (fun t -> t.levels)
+      |+ multi_field "cycle" Cycle.rpc_arg (fun t -> t.cycles)
       |+ multi_field "delegate" Signature.Public_key_hash.rpc_arg (fun t -> t.delegates)
       |+ opt_field "max_priority" RPC_arg.int (fun t -> t.max_priority)
       |+ flag "all" (fun t -> t.all)
@@ -437,8 +437,8 @@ module Endorsing_rights = struct
       let open RPC_query in
       query (fun levels cycles delegates ->
           { levels ; cycles ; delegates })
-      |+ multi_field "level" Raw_level.arg (fun t -> t.levels)
-      |+ multi_field "cycle" Cycle.arg (fun t -> t.cycles)
+      |+ multi_field "level" Raw_level.rpc_arg (fun t -> t.levels)
+      |+ multi_field "cycle" Cycle.rpc_arg (fun t -> t.cycles)
       |+ multi_field "delegate" Signature.Public_key_hash.rpc_arg (fun t -> t.delegates)
       |> seal
 
diff --git a/src/proto_alpha/lib_protocol/src/raw_level_repr.ml b/src/proto_alpha/lib_protocol/src/raw_level_repr.ml
index b00ec13c4..4d473bb52 100644
--- a/src/proto_alpha/lib_protocol/src/raw_level_repr.ml
+++ b/src/proto_alpha/lib_protocol/src/raw_level_repr.ml
@@ -12,7 +12,7 @@ type raw_level = t
 include (Compare.Int32 : Compare.S with type t := t)
 let encoding = Data_encoding.int32
 let pp ppf level = Format.fprintf ppf "%ld" level
-let arg =
+let rpc_arg =
   let construct raw_level = Int32.to_string raw_level in
   let destruct str =
     match Int32.of_string str with
diff --git a/src/proto_alpha/lib_protocol/src/raw_level_repr.mli b/src/proto_alpha/lib_protocol/src/raw_level_repr.mli
index c70d9bd8a..40fe1615e 100644
--- a/src/proto_alpha/lib_protocol/src/raw_level_repr.mli
+++ b/src/proto_alpha/lib_protocol/src/raw_level_repr.mli
@@ -13,7 +13,7 @@
 type t
 type raw_level = t
 val encoding: raw_level Data_encoding.t
-val arg: raw_level RPC_arg.arg
+val rpc_arg: raw_level RPC_arg.arg
 val pp: Format.formatter -> raw_level -> unit
 include Compare.S with type t := raw_level
 
diff --git a/src/proto_alpha/lib_protocol/src/roll_repr.ml b/src/proto_alpha/lib_protocol/src/roll_repr.ml
index 053cba14d..dcedbb4fd 100644
--- a/src/proto_alpha/lib_protocol/src/roll_repr.ml
+++ b/src/proto_alpha/lib_protocol/src/roll_repr.ml
@@ -18,6 +18,11 @@ let succ i = Int32.succ i
 let random sequence ~bound =
   Seed_repr.take_int32 sequence bound
 
+let rpc_arg =
+  RPC_arg.like
+    RPC_arg.int32
+    "roll"
+
 let to_int32 v = v
 
 let (=) = Compare.Int32.(=)
diff --git a/src/proto_alpha/lib_protocol/src/roll_repr.mli b/src/proto_alpha/lib_protocol/src/roll_repr.mli
index 69035782a..ceaf736bd 100644
--- a/src/proto_alpha/lib_protocol/src/roll_repr.mli
+++ b/src/proto_alpha/lib_protocol/src/roll_repr.mli
@@ -11,6 +11,7 @@ type t = private int32
 type roll = t
 
 val encoding: roll Data_encoding.t
+val rpc_arg: roll RPC_arg.t
 
 val random:
   Seed_repr.sequence -> bound:roll -> roll * Seed_repr.sequence
diff --git a/src/proto_alpha/lib_protocol/src/voting_period_repr.ml b/src/proto_alpha/lib_protocol/src/voting_period_repr.ml
index 177a2cab1..e88bd9d9f 100644
--- a/src/proto_alpha/lib_protocol/src/voting_period_repr.ml
+++ b/src/proto_alpha/lib_protocol/src/voting_period_repr.ml
@@ -12,7 +12,7 @@ type voting_period = t
 include (Compare.Int32 : Compare.S with type t := t)
 let encoding = Data_encoding.int32
 let pp ppf level = Format.fprintf ppf "%ld" level
-let arg =
+let rpc_arg =
   let construct voting_period = Int32.to_string voting_period in
   let destruct str =
     match Int32.of_string str with
diff --git a/src/proto_alpha/lib_protocol/src/voting_period_repr.mli b/src/proto_alpha/lib_protocol/src/voting_period_repr.mli
index d9d6f8c46..f92a7fdf4 100644
--- a/src/proto_alpha/lib_protocol/src/voting_period_repr.mli
+++ b/src/proto_alpha/lib_protocol/src/voting_period_repr.mli
@@ -10,7 +10,7 @@
 type t
 type voting_period = t
 val encoding: voting_period Data_encoding.t
-val arg: voting_period RPC_arg.arg
+val rpc_arg: voting_period RPC_arg.arg
 val pp: Format.formatter -> voting_period -> unit
 include Compare.S with type t := voting_period