[RFC] Type system ordering of: object interfaces, directive arguments, input object fields, enum values

spec/Section 3 -- Type System.md

@@ -302,17 +302,18 @@ enumerable. GraphQL offers an `Enum` type in those cases, where the type
 specifies the space of valid responses.
 
 Scalars and Enums form the leaves in response trees; the intermediate levels are
-`Object` types, which define a set of fields, where each field is another type
-in the system, allowing the definition of arbitrary type hierarchies.
+`Object` types, which define an ordered set of fields, where each field is
+another type in the system, allowing the definition of arbitrary type
+hierarchies.
 
 GraphQL supports two abstract types: interfaces and unions.
 
-An `Interface` defines a list of fields; `Object` types and other Interface
-types which implement this Interface are guaranteed to implement those fields.
-Whenever a field claims it will return an Interface type, it will return a valid
-implementing Object type during execution.
+An `Interface` defines an ordered set of fields; `Object` types and other
+Interface types which implement this Interface are guaranteed to implement those
+fields (in any order). Whenever a field claims it will return an Interface type,
+it will return a valid implementing Object type during execution.
 
-A `Union` defines a list of possible types; similar to interfaces, whenever the
+A `Union` defines a set of possible types; similar to interfaces, whenever the
 type system claims a union will be returned, one of the possible types will be
 returned.
 
@@ -674,11 +675,11 @@ GraphQL operations are hierarchical and composed, describing a tree of
 information. While Scalar types describe the leaf values of these hierarchical
 operations, Objects describe the intermediate levels.
 
-GraphQL Objects represent a list of named fields, each of which yield a value of
-a specific type. Object values should be serialized as ordered maps, where the
-selected field names (or aliases) are the keys and the result of evaluating the
-field is the value, ordered by the order in which they appear in the _selection
-set_.
+GraphQL Objects represent an ordered set of named fields, each of which yield a
+value of a specific type. Object values should be serialized as ordered maps,
+where the selected field names (or aliases) are the keys and the result of
+evaluating the field is the value, ordered by the order in which they appear in
+the _selection set_.
 
 All fields defined within an Object type must not have a name which begins with
 {"\_\_"} (two underscores), as this is used exclusively by GraphQL's
@@ -920,7 +921,8 @@ of rules must be adhered to by every Object type in a GraphQL schema.
          returns {true}.
       4. If argument type is Non-Null and a default value is not defined:
          1. The `@deprecated` directive must not be applied to this argument.
-3. An object type may declare that it implements one or more unique interfaces.
+3. An object type may declare that it implements one or more unique interfaces,
+   these interfaces form an ordered set.
 4. An object type must be a super-set of all interfaces it implements:
    1. Let this object type be {objectType}.
    2. For each interface declared implemented as {interfaceType},
@@ -982,7 +984,7 @@ InputValueDefinition : Description? Name : Type DefaultValue? Directives[Const]?
 
 Object fields are conceptually functions which yield values. Occasionally object
 fields can accept arguments to further specify the return value. Object field
-arguments are defined as a list of all possible argument names and their
+arguments are defined as an ordered set of all possible argument names and their
 expected input types.
 
 All arguments defined within a field must not have a name which begins with
@@ -1093,9 +1095,10 @@ InterfaceTypeDefinition :
 - Description? interface Name ImplementsInterfaces? Directives[Const]?
   [lookahead != `{`]
 
-GraphQL interfaces represent a list of named fields and their arguments. GraphQL
-objects and interfaces can then implement these interfaces which requires that
-the implementing type will define all fields defined by those interfaces.
+GraphQL interfaces represent an ordered set of named fields and their arguments.
+GraphQL objects and interfaces can then implement these interfaces which
+requires that the implementing type will define all fields defined by those
+interfaces.
 
 Fields on a GraphQL interface have the same rules as fields on a GraphQL object;
 their type can be Scalar, Object, Enum, Interface, or Union, or any wrapping
@@ -1347,10 +1350,10 @@ UnionMemberTypes :
 - UnionMemberTypes | NamedType
 - = `|`? NamedType
 
-GraphQL Unions represent an object that could be one of a list of GraphQL Object
-types, but provides for no guaranteed fields between those types. They also
-differ from interfaces in that Object types declare what interfaces they
-implement, but are not aware of what unions contain them.
+GraphQL Unions represent an object that could be one of an ordered set of
+GraphQL Object types, but provides for no guaranteed fields between those types.
+They also differ from interfaces in that Object types declare what interfaces
+they implement, but are not aware of what unions contain them.
 
 With interfaces and objects, only those fields defined on the type can be
 queried directly; to query other fields on an interface, typed fragments must be
@@ -1408,7 +1411,7 @@ A valid operation includes typed fragments (in this example, inline fragments):
 ```
 
 Union members may be defined with an optional leading `|` character to aid
-formatting when representing a longer list of possible types:
+formatting when representing a longer set of possible types:
 
 ```raw graphql example
 union SearchResult =
@@ -1547,9 +1550,9 @@ InputFieldsDefinition : { InputValueDefinition+ }
 Fields may accept arguments to configure their behavior. These inputs are often
 scalars or enums, but they sometimes need to represent more complex values.
 
-A GraphQL Input Object defines a set of input fields; the input fields are
-either scalars, enums, or other input objects. This allows arguments to accept
-arbitrarily complex structs.
+A GraphQL Input Object defines an ordered set of named input fields; the input
+fields are either scalars, enums, or other input objects. This allows arguments
+to accept arbitrarily complex structs.
 
 In this example, an Input Object called `Point2D` describes `x` and `y` inputs:
 
@@ -1936,6 +1939,10 @@ A GraphQL schema describes directives which are used to annotate various parts
 of a GraphQL document as an indicator that they should be evaluated differently
 by a validator, executor, or client tool such as a code generator.
 
+Directives can accept arguments to further specify their behavior. Directive
+arguments are defined as an ordered set of all possible argument names and their
+expected input types.
+
 **Built-in Directives**
 
 :: A _built-in directive_ is any directive defined within this specification.
@@ -1983,7 +1990,7 @@ fragment SomeFragment on SomeType {
 ```
 
 Directive locations may be defined with an optional leading `|` character to aid
-formatting when representing a longer list of possible locations:
+formatting when representing a longer set of possible locations:
 
 ```raw graphql example
 directive @example on