diff --git a/CHANGELOG.md b/CHANGELOG.md
index 96150677..cf20798c 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ## Unreleased
 
 - Use Rust `2021` edition.
+- Subscription typename - [GraphQL - October 2021] [#681](https://github.com/async-graphql/async-graphql/issues/681)
+- Allow directive on variable definition - [GraphQL - October 2021] [#678](https://github.com/async-graphql/async-graphql/issues/678)
+- Specified By - [GraphQL - October 2021] [#677](https://github.com/async-graphql/async-graphql/issues/677)
+- Add `specified_by_url` for `Tz`, `DateTime<Tz>`, `Url`, `Uuid` and `Upload` scalars.
 
 ## [2.10.8] 2021-10-26
 
diff --git a/derive/src/args.rs b/derive/src/args.rs
index e2ba5e86..4985953a 100644
--- a/derive/src/args.rs
+++ b/derive/src/args.rs
@@ -446,6 +446,7 @@ pub struct Scalar {
     pub name: Option<String>,
     pub use_type_description: bool,
     pub visible: Option<Visible>,
+    pub specified_by_url: Option<String>,
 }
 
 #[derive(FromMeta, Default)]
@@ -652,6 +653,8 @@ pub struct NewType {
     pub name: NewTypeName,
     #[darling(default)]
     pub visible: Option<Visible>,
+    #[darling(default)]
+    pub specified_by_url: Option<String>,
 }
 
 #[derive(FromMeta, Default)]
diff --git a/derive/src/merged_object.rs b/derive/src/merged_object.rs
index f6ccc3fb..3ea5b313 100644
--- a/derive/src/merged_object.rs
+++ b/derive/src/merged_object.rs
@@ -90,6 +90,7 @@ pub fn generate(object_args: &args::MergedObject) -> GeneratorResult<TokenStream
                         extends: #extends,
                         keys: ::std::option::Option::None,
                         visible: #visible,
+                        is_subscription: false,
                     }
                 })
             }
diff --git a/derive/src/merged_subscription.rs b/derive/src/merged_subscription.rs
index 2b57dea8..4ce2d6ca 100644
--- a/derive/src/merged_subscription.rs
+++ b/derive/src/merged_subscription.rs
@@ -72,6 +72,7 @@ pub fn generate(object_args: &args::MergedSubscription) -> GeneratorResult<Token
                         extends: #extends,
                         keys: ::std::option::Option::None,
                         visible: #visible,
+                        is_subscription: true,
                     }
                 })
             }
diff --git a/derive/src/newtype.rs b/derive/src/newtype.rs
index cc00ceec..d15ee1f5 100644
--- a/derive/src/newtype.rs
+++ b/derive/src/newtype.rs
@@ -38,12 +38,18 @@ pub fn generate(newtype_args: &args::NewType) -> GeneratorResult<TokenStream> {
         None => quote! { <#inner_ty as #crate_name::Type>::type_name() },
     };
     let create_type_info = if let Some(name) = &gql_typename {
+        let specified_by_url = match &newtype_args.specified_by_url {
+            Some(specified_by_url) => quote! { ::std::option::Option::Some(#specified_by_url) },
+            None => quote! { ::std::option::Option::None },
+        };
+
         quote! {
             registry.create_type::<#ident, _>(|_| #crate_name::registry::MetaType::Scalar {
                 name: ::std::borrow::ToOwned::to_owned(#name),
                 description: #desc,
                 is_valid: |value| <#ident as #crate_name::ScalarType>::is_valid(value),
                 visible: #visible,
+                specified_by_url: #specified_by_url,
             })
         }
     } else {
diff --git a/derive/src/object.rs b/derive/src/object.rs
index 665a9976..94fa4e89 100644
--- a/derive/src/object.rs
+++ b/derive/src/object.rs
@@ -563,6 +563,7 @@ pub fn generate(
                         extends: #extends,
                         keys: ::std::option::Option::None,
                         visible: #visible,
+                        is_subscription: false,
                     });
                     #(#create_entity_types)*
                     #(#add_keys)*
@@ -630,6 +631,7 @@ pub fn generate(
                         extends: #extends,
                         keys: ::std::option::Option::None,
                         visible: #visible,
+                        is_subscription: false,
                     });
                     #(#create_entity_types)*
                     #(#add_keys)*
diff --git a/derive/src/scalar.rs b/derive/src/scalar.rs
index 561ee384..3aa55b0a 100644
--- a/derive/src/scalar.rs
+++ b/derive/src/scalar.rs
@@ -30,6 +30,11 @@ pub fn generate(
     let generic = &item_impl.generics;
     let where_clause = &item_impl.generics.where_clause;
     let visible = visible_fn(&scalar_args.visible);
+    let specified_by_url = match &scalar_args.specified_by_url {
+        Some(specified_by_url) => quote! { ::std::option::Option::Some(#specified_by_url) },
+        None => quote! { ::std::option::Option::None },
+    };
+
     let expanded = quote! {
         #item_impl
 
@@ -45,6 +50,7 @@ pub fn generate(
                     description: #desc,
                     is_valid: |value| <#self_ty as #crate_name::ScalarType>::is_valid(value),
                     visible: #visible,
+                    specified_by_url: #specified_by_url,
                 })
             }
         }
diff --git a/derive/src/simple_object.rs b/derive/src/simple_object.rs
index a170749d..a603e8cb 100644
--- a/derive/src/simple_object.rs
+++ b/derive/src/simple_object.rs
@@ -293,6 +293,7 @@ pub fn generate(object_args: &args::SimpleObject) -> GeneratorResult<TokenStream
                         extends: #extends,
                         keys: ::std::option::Option::None,
                         visible: #visible,
+                        is_subscription: false,
                     })
                 }
             }
@@ -343,6 +344,7 @@ pub fn generate(object_args: &args::SimpleObject) -> GeneratorResult<TokenStream
                         extends: #extends,
                         keys: ::std::option::Option::None,
                         visible: #visible,
+                        is_subscription: false,
                     })
                 }
 
diff --git a/derive/src/subscription.rs b/derive/src/subscription.rs
index b4a7b908..6693e9cd 100644
--- a/derive/src/subscription.rs
+++ b/derive/src/subscription.rs
@@ -456,6 +456,7 @@ pub fn generate(
                     extends: #extends,
                     keys: ::std::option::Option::None,
                     visible: ::std::option::Option::None,
+                    is_subscription: true,
                 })
             }
         }
diff --git a/parser/src/graphql.pest b/parser/src/graphql.pest
index 1a7fcd5b..12cff935 100644
--- a/parser/src/graphql.pest
+++ b/parser/src/graphql.pest
@@ -10,7 +10,7 @@ executable_definition = { operation_definition | fragment_definition }
 operation_definition       = { named_operation_definition | selection_set }
 named_operation_definition = { operation_type ~ name? ~ variable_definitions? ~ directives? ~ selection_set }
 variable_definitions       = { "(" ~ variable_definition* ~ ")" }
-variable_definition        = { variable ~ ":" ~ type_ ~ default_value? }
+variable_definition        = { variable ~ ":" ~ type_ ~ directives? ~ default_value? }
 
 selection_set = { "{" ~ selection+ ~ "}" }
 selection = { field | inline_fragment | fragment_spread }
@@ -86,6 +86,7 @@ directive_location = {
 	| "FRAGMENT_DEFINITION"
 	| "FRAGMENT_SPREAD"
 	| "INLINE_FRAGMENT"
+	| "VARIABLE_DEFINITION"
 	| "SCHEMA"
 	| "SCALAR"
 	| "OBJECT"
@@ -115,7 +116,7 @@ value       = { variable | number | string | boolean | null | enum_value |
 
 variable = { "$" ~ name }
 
-number     = @{ float | int }
+number     = @{ (float | int) ~ !name_start }
 float      = { int ~ ((fractional ~ exponent) | fractional | exponent) }
 fractional = { "." ~ ASCII_DIGIT+ }
 exponent   = { ("E" | "e") ~ ("+" | "-")? ~ ASCII_DIGIT+ }
@@ -164,4 +165,5 @@ arguments       = { "(" ~       argument+ ~ ")" }
 const_argument = { name ~ ":" ~ const_value }
 argument       = { name ~ ":" ~       value }
 
-name = @{ (ASCII_ALPHA | "_") ~ (ASCII_ALPHA | ASCII_DIGIT | "_")* }
+name_start = @{ (ASCII_ALPHA | "_") }
+name = @{ name_start ~ (ASCII_ALPHA | ASCII_DIGIT | "_")* }
diff --git a/parser/src/parse/executable.rs b/parser/src/parse/executable.rs
index 2fc2a1e6..6ec0207d 100644
--- a/parser/src/parse/executable.rs
+++ b/parser/src/parse/executable.rs
@@ -208,6 +208,8 @@ fn parse_variable_definition(
 
     let variable = parse_variable(pairs.next().unwrap(), pc)?;
     let var_type = parse_type(pairs.next().unwrap(), pc)?;
+
+    let directives = parse_opt_directives(&mut pairs, pc)?;
     let default_value = parse_if_rule(&mut pairs, Rule::default_value, |pair| {
         parse_default_value(pair, pc)
     })?;
@@ -218,6 +220,7 @@ fn parse_variable_definition(
         VariableDefinition {
             name: variable,
             var_type,
+            directives,
             default_value,
         },
         pos,
diff --git a/parser/src/parse/mod.rs b/parser/src/parse/mod.rs
index 54c10963..3a3e4259 100644
--- a/parser/src/parse/mod.rs
+++ b/parser/src/parse/mod.rs
@@ -312,3 +312,21 @@ fn parse_name(pair: Pair<Rule>, pc: &mut PositionCalculator) -> Result<Positione
     debug_assert_eq!(pair.as_rule(), Rule::name);
     Ok(Positioned::new(Name::new(pair.as_str()), pc.step(&pair)))
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_number_lookahead_restrictions() {
+        GraphQLParser::parse(Rule::const_list, "[123 abc]").unwrap();
+        GraphQLParser::parse(Rule::const_list, "[123.0123 abc]").unwrap();
+        GraphQLParser::parse(Rule::const_list, "[123.0123e7 abc]").unwrap();
+        GraphQLParser::parse(Rule::const_list, "[123.0123e77 abc]").unwrap();
+
+        assert!(GraphQLParser::parse(Rule::const_list, "[123abc]").is_err());
+        assert!(GraphQLParser::parse(Rule::const_list, "[123.0123abc]").is_err());
+        assert!(GraphQLParser::parse(Rule::const_list, "[123.0123e7abc]").is_err());
+        assert!(GraphQLParser::parse(Rule::const_list, "[123.0123e77abc]").is_err());
+    }
+}
diff --git a/parser/src/parse/service.rs b/parser/src/parse/service.rs
index 9b2c6206..fa71f235 100644
--- a/parser/src/parse/service.rs
+++ b/parser/src/parse/service.rs
@@ -323,6 +323,7 @@ fn parse_directive_definition(
                         "FRAGMENT_DEFINITION" => DirectiveLocation::FragmentDefinition,
                         "FRAGMENT_SPREAD" => DirectiveLocation::FragmentSpread,
                         "INLINE_FRAGMENT" => DirectiveLocation::InlineFragment,
+                        "VARIABLE_DEFINITION" => DirectiveLocation::VariableDefinition,
                         "SCHEMA" => DirectiveLocation::Schema,
                         "SCALAR" => DirectiveLocation::Scalar,
                         "OBJECT" => DirectiveLocation::Object,
diff --git a/parser/src/pos.rs b/parser/src/pos.rs
index 3f37e3e7..a52b062f 100644
--- a/parser/src/pos.rs
+++ b/parser/src/pos.rs
@@ -10,7 +10,7 @@ use std::str::Chars;
 /// Original position of an element in source code.
 ///
 /// You can serialize and deserialize it to the GraphQL `locations` format
-/// ([reference](https://spec.graphql.org/June2018/#sec-Errors)).
+/// ([reference](https://spec.graphql.org/October2021/#sec-Errors)).
 #[derive(PartialOrd, Ord, PartialEq, Eq, Clone, Copy, Default, Hash, Serialize, Deserialize)]
 pub struct Pos {
     /// One-based line number.
diff --git a/parser/src/types/executable.rs b/parser/src/types/executable.rs
index 88371ac1..0e70b13a 100644
--- a/parser/src/types/executable.rs
+++ b/parser/src/types/executable.rs
@@ -5,7 +5,7 @@ use async_graphql_value::{ConstValue, Name, Value};
 
 /// An executable GraphQL file or request string.
 ///
-/// [Reference](https://spec.graphql.org/June2018/#ExecutableDocument).
+/// [Reference](https://spec.graphql.org/October2021/#ExecutableDocument).
 #[derive(Debug, Clone)]
 pub struct ExecutableDocument {
     /// The operations of the document.
@@ -93,7 +93,7 @@ enum OperationsIterInner<'a> {
 
 /// A GraphQL operation, such as `mutation($content:String!) { makePost(content: $content) { id } }`.
 ///
-/// [Reference](https://spec.graphql.org/June2018/#OperationDefinition).
+/// [Reference](https://spec.graphql.org/October2021/#OperationDefinition).
 #[derive(Debug, Clone)]
 pub struct OperationDefinition {
     /// The type of operation.
@@ -108,13 +108,15 @@ pub struct OperationDefinition {
 
 /// A variable definition inside a list of variable definitions, for example `$name:String!`.
 ///
-/// [Reference](https://spec.graphql.org/June2018/#VariableDefinition).
+/// [Reference](https://spec.graphql.org/October2021/#VariableDefinition).
 #[derive(Debug, Clone)]
 pub struct VariableDefinition {
     /// The name of the variable, without the preceding `$`.
     pub name: Positioned<Name>,
     /// The type of the variable.
     pub var_type: Positioned<Type>,
+    /// The variable's directives.
+    pub directives: Vec<Positioned<Directive>>,
     /// The optional default value of the variable.
     pub default_value: Option<Positioned<ConstValue>>,
 }
@@ -139,7 +141,7 @@ impl VariableDefinition {
 
 /// A set of fields to be selected, for example `{ name age }`.
 ///
-/// [Reference](https://spec.graphql.org/June2018/#SelectionSet).
+/// [Reference](https://spec.graphql.org/October2021/#SelectionSet).
 #[derive(Debug, Default, Clone)]
 pub struct SelectionSet {
     /// The fields to be selected.
@@ -148,7 +150,7 @@ pub struct SelectionSet {
 
 /// A part of an object to be selected; a single field, a fragment spread or an inline fragment.
 ///
-/// [Reference](https://spec.graphql.org/June2018/#Selection).
+/// [Reference](https://spec.graphql.org/October2021/#Selection).
 #[derive(Debug, Clone)]
 pub enum Selection {
     /// Select a single field, such as `name` or `weightKilos: weight(unit: KILOGRAMS)`.
@@ -182,7 +184,7 @@ impl Selection {
 
 /// A field being selected on an object, such as `name` or `weightKilos: weight(unit: KILOGRAMS)`.
 ///
-/// [Reference](https://spec.graphql.org/June2018/#Field).
+/// [Reference](https://spec.graphql.org/October2021/#Field).
 #[derive(Debug, Clone)]
 pub struct Field {
     /// The optional field alias.
@@ -217,7 +219,7 @@ impl Field {
 
 /// A fragment selector, such as `... userFields`.
 ///
-/// [Reference](https://spec.graphql.org/June2018/#FragmentSpread).
+/// [Reference](https://spec.graphql.org/October2021/#FragmentSpread).
 #[derive(Debug, Clone)]
 pub struct FragmentSpread {
     /// The name of the fragment being selected.
@@ -228,7 +230,7 @@ pub struct FragmentSpread {
 
 /// An inline fragment selector, such as `... on User { name }`.
 ///
-/// [Reference](https://spec.graphql.org/June2018/#InlineFragment).
+/// [Reference](https://spec.graphql.org/October2021/#InlineFragment).
 #[derive(Debug, Clone)]
 pub struct InlineFragment {
     /// The type condition.
@@ -241,7 +243,7 @@ pub struct InlineFragment {
 
 /// The definition of a fragment, such as `fragment userFields on User { name age }`.
 ///
-/// [Reference](https://spec.graphql.org/June2018/#FragmentDefinition).
+/// [Reference](https://spec.graphql.org/October2021/#FragmentDefinition).
 #[derive(Debug, Clone)]
 pub struct FragmentDefinition {
     /// The type this fragment operates on.
@@ -254,7 +256,7 @@ pub struct FragmentDefinition {
 
 /// A type a fragment can apply to (`on` followed by the type).
 ///
-/// [Reference](https://spec.graphql.org/June2018/#TypeCondition).
+/// [Reference](https://spec.graphql.org/October2021/#TypeCondition).
 #[derive(Debug, Clone)]
 pub struct TypeCondition {
     /// The type this fragment applies to.
diff --git a/parser/src/types/mod.rs b/parser/src/types/mod.rs
index b52e35d2..151fa94f 100644
--- a/parser/src/types/mod.rs
+++ b/parser/src/types/mod.rs
@@ -4,7 +4,7 @@
 //! [`ServiceDocument`](struct.ServiceDocument.html), representing an executable GraphQL query and a
 //! GraphQL service respectively.
 //!
-//! This follows the [June 2018 edition of the GraphQL spec](https://spec.graphql.org/June2018/).
+//! This follows the [June 2018 edition of the GraphQL spec](https://spec.graphql.org/October2021/).
 
 mod executable;
 mod service;
@@ -19,7 +19,7 @@ pub use service::*;
 
 /// The type of an operation; `query`, `mutation` or `subscription`.
 ///
-/// [Reference](https://spec.graphql.org/June2018/#OperationType).
+/// [Reference](https://spec.graphql.org/October2021/#OperationType).
 #[derive(Debug, PartialEq, Eq, Copy, Clone)]
 pub enum OperationType {
     /// A query.
@@ -42,7 +42,7 @@ impl Display for OperationType {
 
 /// A GraphQL type, for example `String` or `[String!]!`.
 ///
-/// [Reference](https://spec.graphql.org/June2018/#Type).
+/// [Reference](https://spec.graphql.org/October2021/#Type).
 #[derive(Debug, PartialEq, Eq, Clone)]
 pub struct Type {
     /// The base type.
@@ -105,7 +105,7 @@ impl Display for BaseType {
 /// from [`Directive`](struct.Directive.html) in that it uses [`ConstValue`](enum.ConstValue.html)
 /// instead of [`Value`](enum.Value.html).
 ///
-/// [Reference](https://spec.graphql.org/June2018/#Directive).
+/// [Reference](https://spec.graphql.org/October2021/#Directive).
 #[derive(Debug, Clone)]
 pub struct ConstDirective {
     /// The name of the directive.
@@ -140,7 +140,7 @@ impl ConstDirective {
 
 /// A GraphQL directive, such as `@deprecated(reason: "Use the other field")`.
 ///
-/// [Reference](https://spec.graphql.org/June2018/#Directive).
+/// [Reference](https://spec.graphql.org/October2021/#Directive).
 #[derive(Debug, Clone)]
 pub struct Directive {
     /// The name of the directive.
diff --git a/parser/src/types/service.rs b/parser/src/types/service.rs
index 2a3e81f5..f5e2bcdb 100644
--- a/parser/src/types/service.rs
+++ b/parser/src/types/service.rs
@@ -5,7 +5,7 @@ use async_graphql_value::Name;
 
 /// A GraphQL file or request string defining a GraphQL service.
 ///
-/// [Reference](https://spec.graphql.org/June2018/#Document).
+/// [Reference](https://spec.graphql.org/October2021/#Document).
 #[derive(Debug, Clone)]
 pub struct ServiceDocument {
     /// The definitions of this document.
@@ -14,8 +14,8 @@ pub struct ServiceDocument {
 
 /// A definition concerning the type system of a GraphQL service.
 ///
-/// [Reference](https://spec.graphql.org/June2018/#TypeSystemDefinition). This enum also covers
-/// [extensions](https://spec.graphql.org/June2018/#TypeSystemExtension).
+/// [Reference](https://spec.graphql.org/October2021/#TypeSystemDefinition). This enum also covers
+/// [extensions](https://spec.graphql.org/October2021/#TypeSystemExtension).
 #[derive(Debug, Clone)]
 pub enum TypeSystemDefinition {
     /// The definition of the schema of the service.
@@ -28,8 +28,8 @@ pub enum TypeSystemDefinition {
 
 /// The definition of the schema in a GraphQL service.
 ///
-/// [Reference](https://spec.graphql.org/June2018/#SchemaDefinition). This also covers
-/// [extensions](https://spec.graphql.org/June2018/#SchemaExtension).
+/// [Reference](https://spec.graphql.org/October2021/#SchemaDefinition). This also covers
+/// [extensions](https://spec.graphql.org/October2021/#SchemaExtension).
 #[derive(Debug, Clone)]
 pub struct SchemaDefinition {
     /// Whether the schema is an extension of another schema.
@@ -46,8 +46,8 @@ pub struct SchemaDefinition {
 
 /// The definition of a type in a GraphQL service.
 ///
-/// [Reference](https://spec.graphql.org/June2018/#TypeDefinition). This also covers
-/// [extensions](https://spec.graphql.org/June2018/#TypeExtension).
+/// [Reference](https://spec.graphql.org/October2021/#TypeDefinition). This also covers
+/// [extensions](https://spec.graphql.org/October2021/#TypeExtension).
 #[derive(Debug, Clone)]
 pub struct TypeDefinition {
     /// Whether the type is an extension of another type.
@@ -81,7 +81,7 @@ pub enum TypeKind {
 
 /// The definition of an object type.
 ///
-/// [Reference](https://spec.graphql.org/June2018/#ObjectType).
+/// [Reference](https://spec.graphql.org/October2021/#ObjectType).
 #[derive(Debug, Clone)]
 pub struct ObjectType {
     /// The interfaces implemented by the object.
@@ -92,7 +92,7 @@ pub struct ObjectType {
 
 /// The definition of a field inside an object or interface.
 ///
-/// [Reference](https://spec.graphql.org/June2018/#FieldDefinition).
+/// [Reference](https://spec.graphql.org/October2021/#FieldDefinition).
 #[derive(Debug, Clone)]
 pub struct FieldDefinition {
     /// The description of the field.
@@ -109,7 +109,7 @@ pub struct FieldDefinition {
 
 /// The definition of an interface type.
 ///
-/// [Reference](https://spec.graphql.org/June2018/#InterfaceType).
+/// [Reference](https://spec.graphql.org/October2021/#InterfaceType).
 #[derive(Debug, Clone)]
 pub struct InterfaceType {
     /// The interfaces implemented by the interface.
@@ -120,7 +120,7 @@ pub struct InterfaceType {
 
 /// The definition of a union type.
 ///
-/// [Reference](https://spec.graphql.org/June2018/#UnionType).
+/// [Reference](https://spec.graphql.org/October2021/#UnionType).
 #[derive(Debug, Clone)]
 pub struct UnionType {
     /// The member types of the union.
@@ -129,7 +129,7 @@ pub struct UnionType {
 
 /// The definition of an enum.
 ///
-/// [Reference](https://spec.graphql.org/June2018/#EnumType).
+/// [Reference](https://spec.graphql.org/October2021/#EnumType).
 #[derive(Debug, Clone)]
 pub struct EnumType {
     /// The possible values of the enum.
@@ -138,7 +138,7 @@ pub struct EnumType {
 
 /// The definition of a value inside an enum.
 ///
-/// [Reference](https://spec.graphql.org/June2018/#EnumValueDefinition).
+/// [Reference](https://spec.graphql.org/October2021/#EnumValueDefinition).
 #[derive(Debug, Clone)]
 pub struct EnumValueDefinition {
     /// The description of the argument.
@@ -151,7 +151,7 @@ pub struct EnumValueDefinition {
 
 /// The definition of an input object.
 ///
-/// [Reference](https://spec.graphql.org/June2018/#InputObjectType).
+/// [Reference](https://spec.graphql.org/October2021/#InputObjectType).
 #[derive(Debug, Clone)]
 pub struct InputObjectType {
     /// The fields of the input object.
@@ -160,7 +160,7 @@ pub struct InputObjectType {
 
 /// The definition of an input value inside the arguments of a field.
 ///
-/// [Reference](https://spec.graphql.org/June2018/#InputValueDefinition).
+/// [Reference](https://spec.graphql.org/October2021/#InputValueDefinition).
 #[derive(Debug, Clone)]
 pub struct InputValueDefinition {
     /// The description of the argument.
@@ -177,7 +177,7 @@ pub struct InputValueDefinition {
 
 /// The definition of a directive in a service.
 ///
-/// [Reference](https://spec.graphql.org/June2018/#DirectiveDefinition).
+/// [Reference](https://spec.graphql.org/October2021/#DirectiveDefinition).
 #[derive(Debug, Clone)]
 pub struct DirectiveDefinition {
     /// The description of the directive.
@@ -192,7 +192,7 @@ pub struct DirectiveDefinition {
 
 /// Where a directive can apply to.
 ///
-/// [Reference](https://spec.graphql.org/June2018/#DirectiveLocation).
+/// [Reference](https://spec.graphql.org/October2021/#DirectiveLocation).
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
 pub enum DirectiveLocation {
     /// A [query](enum.OperationType.html#variant.Query) [operation](struct.OperationDefinition.html).
@@ -233,4 +233,6 @@ pub enum DirectiveLocation {
     /// An [input value definition](struct.InputValueDefinition.html) on an input object but not a
     /// field.
     InputFieldDefinition,
+    /// An [variable definition](struct.VariableDefinition.html).
+    VariableDefinition,
 }
diff --git a/parser/tests/executables/variable_directive.graphql b/parser/tests/executables/variable_directive.graphql
new file mode 100644
index 00000000..b6a9d07b
--- /dev/null
+++ b/parser/tests/executables/variable_directive.graphql
@@ -0,0 +1,3 @@
+query Foo($a: Int @directive = 10, $b: Int @directive) {
+    value
+}
diff --git a/parser/tests/services/directive.graphql b/parser/tests/services/directive.graphql
index 401b6f43..456904bd 100644
--- a/parser/tests/services/directive.graphql
+++ b/parser/tests/services/directive.graphql
@@ -4,3 +4,5 @@ directive @test1(service: String!) on FIELD_DEFINITION
 directive @test2(service: String!) on FIELD
 directive @test3(service: String!) on ENUM_VALUE
 directive @test4(service: String!) on ENUM
+
+directive @test5(service: String!) on VARIABLE_DEFINITION
diff --git a/src/lib.rs b/src/lib.rs
index 1d80fb24..4141c381 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -987,6 +987,7 @@ pub use async_graphql_derive::Subscription;
 /// | Attribute   | description               | Type     | Optional |
 /// |-------------|---------------------------|----------|----------|
 /// | name        | Scalar name               | string   | Y        |
+/// | specified_by_url | Provide a specification URL for this scalar type, it must link to a human-readable specification of the data format, serialization and coercion rules for this scalar. | string | Y |
 ///
 pub use async_graphql_derive::Scalar;
 
@@ -1000,8 +1001,9 @@ pub use async_graphql_derive::Scalar;
 /// |-------------|---------------------------|----------|----------|
 /// | name        | If this attribute is provided then define a new scalar, otherwise it is just a transparent proxy for the internal scalar. | string   | Y      |
 /// | name        | If this attribute is provided then define a new scalar, otherwise it is just a transparent proxy for the internal scalar. | bool   | Y        |
-/// | visible(Only valid for new scalars.)   | If `false`, it will not be displayed in introspection. *[See also the Book](https://async-graphql.github.io/async-graphql/en/visibility.html).* | bool | Y |
-/// | visible(Only valid for new scalars.)   | Call the specified function. If the return value is `false`, it will not be displayed in introspection. | string | Y |
+/// | visible(Only valid for new scalars)   | If `false`, it will not be displayed in introspection. *[See also the Book](https://async-graphql.github.io/async-graphql/en/visibility.html).* | bool | Y |
+/// | visible(Only valid for new scalars)   | Call the specified function. If the return value is `false`, it will not be displayed in introspection. | string | Y |
+/// | specified_by_url(Only valid for new scalars) | Provide a specification URL for this scalar type, it must link to a human-readable specification of the data format, serialization and coercion rules for this scalar. | string | Y |
 ///
 /// # Examples
 ///
diff --git a/src/model/type.rs b/src/model/type.rs
index 4f20506c..b8ddfdb9 100644
--- a/src/model/type.rs
+++ b/src/model/type.rs
@@ -218,4 +218,16 @@ impl<'a> __Type<'a> {
             None
         }
     }
+
+    #[graphql(name = "specifiedByURL")]
+    async fn specified_by_url(&self) -> Option<&'a str> {
+        if let TypeDetail::Named(registry::MetaType::Scalar {
+            specified_by_url, ..
+        }) = &self.detail
+        {
+            *specified_by_url
+        } else {
+            None
+        }
+    }
 }
diff --git a/src/registry/mod.rs b/src/registry/mod.rs
index 254cae2c..efbd4c9f 100644
--- a/src/registry/mod.rs
+++ b/src/registry/mod.rs
@@ -189,6 +189,7 @@ pub enum MetaType {
         description: Option<&'static str>,
         is_valid: fn(value: &Value) -> bool,
         visible: Option<MetaVisibleFn>,
+        specified_by_url: Option<&'static str>,
     },
     Object {
         name: String,
@@ -198,6 +199,7 @@ pub enum MetaType {
         extends: bool,
         keys: Option<Vec<String>>,
         visible: Option<MetaVisibleFn>,
+        is_subscription: bool,
     },
     Interface {
         name: String,
@@ -374,6 +376,7 @@ impl Registry {
                     extends: false,
                     keys: None,
                     visible: None,
+                    is_subscription: false,
                 },
             );
             let ty = f(self);
@@ -507,6 +510,7 @@ impl Registry {
                 extends: false,
                 keys: None,
                 visible: None,
+                is_subscription: false,
             },
         );
 
diff --git a/src/resolver_utils/scalar.rs b/src/resolver_utils/scalar.rs
index 2a788345..062547b0 100644
--- a/src/resolver_utils/scalar.rs
+++ b/src/resolver_utils/scalar.rs
@@ -68,6 +68,9 @@ pub trait ScalarType: Sized + Send {
 /// // Rename to `MV` and add description.
 /// // scalar!(MyValue, "MV", "This is my value");
 ///
+/// // Rename to `MV`, add description and specifiedByURL.
+/// // scalar!(MyValue, "MV", "This is my value", "https://tools.ietf.org/html/rfc4122");
+///
 /// struct Query;
 ///
 /// #[Object]
@@ -92,23 +95,47 @@ pub trait ScalarType: Sized + Send {
 /// ```
 #[macro_export]
 macro_rules! scalar {
+    ($ty:ty, $name:literal, $desc:literal, $specified_by_url:literal) => {
+        $crate::scalar_internal!(
+            $ty,
+            $name,
+            ::std::option::Option::Some($desc),
+            ::std::option::Option::Some($specified_by_url)
+        );
+    };
+
     ($ty:ty, $name:literal, $desc:literal) => {
-        $crate::scalar_internal!($ty, $name, ::std::option::Option::Some($desc));
+        $crate::scalar_internal!(
+            $ty,
+            $name,
+            ::std::option::Option::Some($desc),
+            ::std::option::Option::None
+        );
     };
 
     ($ty:ty, $name:literal) => {
-        $crate::scalar_internal!($ty, $name, ::std::option::Option::None);
+        $crate::scalar_internal!(
+            $ty,
+            $name,
+            ::std::option::Option::None,
+            ::std::option::Option::None
+        );
     };
 
     ($ty:ty) => {
-        $crate::scalar_internal!($ty, ::std::stringify!($ty), ::std::option::Option::None);
+        $crate::scalar_internal!(
+            $ty,
+            ::std::stringify!($ty),
+            ::std::option::Option::None,
+            ::std::option::Option::None
+        );
     };
 }
 
 #[macro_export]
 #[doc(hidden)]
 macro_rules! scalar_internal {
-    ($ty:ty, $name:expr, $desc:expr) => {
+    ($ty:ty, $name:expr, $desc:expr, $specified_by_url:expr) => {
         impl $crate::Type for $ty {
             fn type_name() -> ::std::borrow::Cow<'static, ::std::primitive::str> {
                 ::std::borrow::Cow::Borrowed($name)
@@ -122,6 +149,7 @@ macro_rules! scalar_internal {
                     description: $desc,
                     is_valid: |value| <$ty as $crate::ScalarType>::is_valid(value),
                     visible: ::std::option::Option::None,
+                    specified_by_url: $specified_by_url,
                 })
             }
         }
diff --git a/src/types/connection/connection_type.rs b/src/types/connection/connection_type.rs
index 9080004a..ff0193c6 100644
--- a/src/types/connection/connection_type.rs
+++ b/src/types/connection/connection_type.rs
@@ -190,6 +190,7 @@ where
                 extends: false,
                 keys: None,
                 visible: None,
+                is_subscription: false,
             }
         })
     }
diff --git a/src/types/connection/edge.rs b/src/types/connection/edge.rs
index f6c893bb..afa69142 100644
--- a/src/types/connection/edge.rs
+++ b/src/types/connection/edge.rs
@@ -107,6 +107,7 @@ where
                 extends: false,
                 keys: None,
                 visible: None,
+                is_subscription: false,
             }
         })
     }
diff --git a/src/types/empty_mutation.rs b/src/types/empty_mutation.rs
index 481a3cb5..da90a82c 100644
--- a/src/types/empty_mutation.rs
+++ b/src/types/empty_mutation.rs
@@ -45,6 +45,7 @@ impl Type for EmptyMutation {
             extends: false,
             keys: None,
             visible: None,
+            is_subscription: false,
         })
     }
 }
diff --git a/src/types/empty_subscription.rs b/src/types/empty_subscription.rs
index 0c98e473..10d28950 100644
--- a/src/types/empty_subscription.rs
+++ b/src/types/empty_subscription.rs
@@ -25,6 +25,7 @@ impl Type for EmptySubscription {
             extends: false,
             keys: None,
             visible: None,
+            is_subscription: true,
         })
     }
 }
diff --git a/src/types/external/chrono_tz.rs b/src/types/external/chrono_tz.rs
index 86d16372..fafefbef 100644
--- a/src/types/external/chrono_tz.rs
+++ b/src/types/external/chrono_tz.rs
@@ -2,7 +2,11 @@ use chrono_tz::Tz;
 
 use crate::{InputValueError, InputValueResult, Scalar, ScalarType, Value};
 
-#[Scalar(internal, name = "TimeZone")]
+#[Scalar(
+    internal,
+    name = "TimeZone",
+    specified_by_url = "http://www.iana.org/time-zones"
+)]
 impl ScalarType for Tz {
     fn parse(value: Value) -> InputValueResult<Self> {
         match value {
diff --git a/src/types/external/datetime.rs b/src/types/external/datetime.rs
index e56167e3..cdcb2de4 100644
--- a/src/types/external/datetime.rs
+++ b/src/types/external/datetime.rs
@@ -5,7 +5,11 @@ use crate::{InputValueError, InputValueResult, Scalar, ScalarType, Value};
 /// Implement the DateTime<FixedOffset> scalar
 ///
 /// The input/output is a string in RFC3339 format.
-#[Scalar(internal, name = "DateTime")]
+#[Scalar(
+    internal,
+    name = "DateTime",
+    specified_by_url = "https://datatracker.ietf.org/doc/html/rfc3339"
+)]
 impl ScalarType for DateTime<FixedOffset> {
     fn parse(value: Value) -> InputValueResult<Self> {
         match &value {
@@ -22,7 +26,11 @@ impl ScalarType for DateTime<FixedOffset> {
 /// Implement the DateTime<Local> scalar
 ///
 /// The input/output is a string in RFC3339 format.
-#[Scalar(internal, name = "DateTime")]
+#[Scalar(
+    internal,
+    name = "DateTime",
+    specified_by_url = "https://datatracker.ietf.org/doc/html/rfc3339"
+)]
 impl ScalarType for DateTime<Local> {
     fn parse(value: Value) -> InputValueResult<Self> {
         match &value {
@@ -39,7 +47,11 @@ impl ScalarType for DateTime<Local> {
 /// Implement the DateTime<Utc> scalar
 ///
 /// The input/output is a string in RFC3339 format.
-#[Scalar(internal, name = "DateTime")]
+#[Scalar(
+    internal,
+    name = "DateTime",
+    specified_by_url = "https://datatracker.ietf.org/doc/html/rfc3339"
+)]
 impl ScalarType for DateTime<Utc> {
     fn parse(value: Value) -> InputValueResult<Self> {
         match &value {
diff --git a/src/types/external/url.rs b/src/types/external/url.rs
index b9a8dda8..110a6e23 100644
--- a/src/types/external/url.rs
+++ b/src/types/external/url.rs
@@ -2,7 +2,7 @@ use url::Url;
 
 use crate::{InputValueError, InputValueResult, Scalar, ScalarType, Value};
 
-#[Scalar(internal)]
+#[Scalar(internal, specified_by_url = "http://url.spec.whatwg.org/")]
 /// URL is a String implementing the [URL Standard](http://url.spec.whatwg.org/)
 impl ScalarType for Url {
     fn parse(value: Value) -> InputValueResult<Self> {
diff --git a/src/types/external/uuid.rs b/src/types/external/uuid.rs
index 917d4cd2..135c72bd 100644
--- a/src/types/external/uuid.rs
+++ b/src/types/external/uuid.rs
@@ -2,7 +2,11 @@ use uuid::Uuid;
 
 use crate::{InputValueError, InputValueResult, Scalar, ScalarType, Value};
 
-#[Scalar(internal, name = "UUID")]
+#[Scalar(
+    internal,
+    name = "UUID",
+    specified_by_url = "http://tools.ietf.org/html/rfc4122"
+)]
 /// A UUID is a unique 128-bit number, stored as 16 octets. UUIDs are parsed as Strings
 /// within GraphQL. UUIDs are used to assign unique identifiers to entities without requiring a central
 /// allocating authority.
diff --git a/src/types/json.rs b/src/types/json.rs
index 065397f9..2444d73f 100644
--- a/src/types/json.rs
+++ b/src/types/json.rs
@@ -85,6 +85,7 @@ impl<T> Type for OutputJson<T> {
             description: None,
             is_valid: |_| true,
             visible: None,
+            specified_by_url: None,
         })
     }
 }
diff --git a/src/types/maybe_undefined.rs b/src/types/maybe_undefined.rs
index 81a6048f..b9768cb3 100644
--- a/src/types/maybe_undefined.rs
+++ b/src/types/maybe_undefined.rs
@@ -6,7 +6,7 @@ use crate::{registry, InputType, InputValueError, InputValueResult, Type, Value}
 
 /// Similar to `Option`, but it has three states, `undefined`, `null` and `x`.
 ///
-/// **Reference:** <https://spec.graphql.org/June2018/#sec-Null-Value>
+/// **Reference:** <https://spec.graphql.org/October2021/#sec-Null-Value>
 ///
 /// # Examples
 ///
diff --git a/src/types/merged_object.rs b/src/types/merged_object.rs
index c3cb026c..7b236ee4 100644
--- a/src/types/merged_object.rs
+++ b/src/types/merged_object.rs
@@ -50,6 +50,7 @@ impl<A: Type, B: Type> Type for MergedObject<A, B> {
                 extends: false,
                 keys: None,
                 visible: None,
+                is_subscription: false,
             }
         })
     }
diff --git a/src/types/upload.rs b/src/types/upload.rs
index 460f8d24..c6ef0fde 100644
--- a/src/types/upload.rs
+++ b/src/types/upload.rs
@@ -111,6 +111,7 @@ impl Type for Upload {
             description: None,
             is_valid: |value| matches!(value, Value::String(_)),
             visible: None,
+            specified_by_url: Some("https://github.com/jaydenseric/graphql-multipart-request-spec"),
         })
     }
 }
diff --git a/src/validation/rules/fields_on_correct_type.rs b/src/validation/rules/fields_on_correct_type.rs
index 343f75f9..1b4ad9ef 100644
--- a/src/validation/rules/fields_on_correct_type.rs
+++ b/src/validation/rules/fields_on_correct_type.rs
@@ -329,4 +329,9 @@ mod tests {
         "#,
         );
     }
+
+    #[test]
+    fn typename_in_subscription_root() {
+        expect_fails_rule!(factory, "subscription { __typename }");
+    }
 }
diff --git a/src/validation/test_harness.rs b/src/validation/test_harness.rs
index 30bf611b..c691be7a 100644
--- a/src/validation/test_harness.rs
+++ b/src/validation/test_harness.rs
@@ -4,6 +4,7 @@
 
 use once_cell::sync::Lazy;
 
+use crate::futures_util::Stream;
 use crate::parser::types::ExecutableDocument;
 use crate::validation::visitor::{visit, RuleError, Visitor, VisitorContext};
 use crate::*;
@@ -345,8 +346,17 @@ impl MutationRoot {
     }
 }
 
-static TEST_HARNESS: Lazy<Schema<QueryRoot, MutationRoot, EmptySubscription>> =
-    Lazy::new(|| Schema::new(QueryRoot, MutationRoot, EmptySubscription));
+pub struct SubscriptionRoot;
+
+#[Subscription(internal)]
+impl SubscriptionRoot {
+    async fn values(&self) -> impl Stream<Item = i32> {
+        futures_util::stream::once(async move { 10 })
+    }
+}
+
+static TEST_HARNESS: Lazy<Schema<QueryRoot, MutationRoot, SubscriptionRoot>> =
+    Lazy::new(|| Schema::new(QueryRoot, MutationRoot, SubscriptionRoot));
 
 pub(crate) fn validate<'a, V, F>(
     doc: &'a ExecutableDocument,
diff --git a/src/validation/visitor.rs b/src/validation/visitor.rs
index 772d4518..0a6024c7 100644
--- a/src/validation/visitor.rs
+++ b/src/validation/visitor.rs
@@ -611,6 +611,17 @@ fn visit_selection<'a, V: Visitor<'a>>(
                         visit_field(v, ctx, field);
                     },
                 );
+            } else if ctx.current_type().map(|ty| match ty {
+                MetaType::Object {
+                    is_subscription, ..
+                } => *is_subscription,
+                _ => false,
+            }) == Some(true)
+            {
+                ctx.report_error(
+                    vec![field.pos],
+                    "Unknown field \"__typename\" on type \"Subscription\".",
+                );
             }
         }
         Selection::FragmentSpread(fragment_spread) => {
diff --git a/tests/scalar.rs b/tests/scalar.rs
index 414dd109..410d37bb 100644
--- a/tests/scalar.rs
+++ b/tests/scalar.rs
@@ -11,7 +11,12 @@ mod test_mod {
 
 #[tokio::test]
 pub async fn test_scalar_macro() {
-    scalar!(test_mod::MyValue, "MV", "DESC");
+    scalar!(
+        test_mod::MyValue,
+        "MV",
+        "DESC",
+        "https://tools.ietf.org/html/rfc4122"
+    );
 
     struct Query;
 
@@ -26,7 +31,7 @@ pub async fn test_scalar_macro() {
     let schema = Schema::new(Query, EmptyMutation, EmptySubscription);
     assert_eq!(
         schema
-            .execute(r#"{ __type(name:"MV") { name description } }"#)
+            .execute(r#"{ __type(name:"MV") { name description specifiedByURL } }"#)
             .await
             .into_result()
             .unwrap()
@@ -35,6 +40,7 @@ pub async fn test_scalar_macro() {
             "__type": {
                 "name": "MV",
                 "description": "DESC",
+                "specifiedByURL": "https://tools.ietf.org/html/rfc4122",
             }
         })
     );