Add Schema Coordinates RFC

Author: magicmark

spec/Appendix C -- Schema Coordinates.md

@@ -0,0 +1,168 @@
+# Appendix: Schema Coordinates
+
+Schema Coordinates are human readable strings that uniquely identify an element defined in a GraphQL Schema.
+
+## Definition 
+
+SchemaCoordinates :
+  - TypeName FieldSpecifier?
+  - InterfaceName FieldSpecifier?
+  - EnumName EnumValueSpecifier?
+  - @ DirectiveName ArgumentSpecifier?
+  - UnionName
+
+FieldSpecifier :
+  - . FieldName ArgumentSpecifier?
+
+ArgumentSpecifier :
+  - ( ArgumentName )
+
+EnumValueSpecifier :
+  - . EnumValue
+
+## Examples
+
+This section shows example coordinates for the possible schema element types this syntax covers.
+
+All examples below will assume the following schema:
+
+```graphql example
+directive @private(scope: String!) on FIELD
+
+interface Address {
+    city: String
+}
+
+type User implements Address {
+    name: String
+    reviewCount: Int
+    friends: [User]
+    email: String @private(scope: 'loggedIn')
+    city: String
+}
+
+type Business implements Address {
+    name: String
+    address: String
+    rating: Int
+    city: String
+}
+
+union Entity = User | Business
+
+enum SearchFilter {
+    OPEN_NOW
+    DELIVERS_TAKEOUT
+    VEGETARIAN_MENU
+}
+
+type Query {
+    searchBusiness(name: String!, filter: SearchFilter): Business
+}
+```
+
+**Selecting a Type**
+
+Schema Coordinates for the `Business` type:
+
+```example
+Business
+```
+
+Schema Coordinates for the `User` type:
+
+```example
+User
+```
+
+**Selecting a Field on a Type**
+
+Schema Coordinates for the `name` field on the `Business` type:
+
+```example
+Business.name
+```
+
+Schema Coordinates for the `name` field on the `User` type:
+
+```example
+User.name
+```
+
+**Selecting an Argument on a Field**
+
+Schema Coordinates for the `name` argument on the `searchBusiness` field on the `Query` type:
+
+```example
+Query.searchBusiness(name)
+```
+
+Schema Coordinates for the `filter` argument on the `searchBusiness` field on the `Query` type:
+
+```example
+Query.searchBusiness(filter)
+```
+
+**Selecting an Enum**
+
+Schema Coordinates for the `SearchFilter` enum:
+
+```example
+SearchFilter
+```
+
+**Selecting an Enum Value**
+
+Schema Coordinates for the `OPEN_NOW` value of the`SearchFilter` enum:
+
+```example
+SearchFilter.OPEN_NOW
+```
+
+**Selecting a Directive Definition**
+
+Schema Coordinates for the `@private` directive definition:
+
+```example
+@private
+```
+
+**Selecting a Directive Definition Argument**
+
+Schema Coordinates for the `scope` argument on the `@private` directive definition:
+
+```example
+@private(scope)
+```
+
+**Selecting an Interface**
+
+Schema Coordinates for the `Address` interface:
+
+```example
+Address
+```
+
+**Selecting a Field on an Interface**
+
+Schema Coordinates for the `city` field on the `Address` interface:
+
+```example
+Address.city
+```
+
+**Selecting a Union**
+
+Schema Coordinates for the `Entity` union definition:
+
+```example
+Entity
+```
+
+You may not select members inside a union definition.
+
+```graphql counter-example
+Entity.Business
+```
+
+In such cases, you may wish to [select the type directly](#sec-Examples.Selecting-a-Type) instead.

spec/GraphQL.md

@@ -127,3 +127,5 @@ Note: This is an example of a non-normative note.
 # [Appendix: Notation Conventions](Appendix%20A%20--%20Notation%20Conventions.md)
 
 # [Appendix: Grammar Summary](Appendix%20B%20--%20Grammar%20Summary.md)
+
+# [Appendix: Schema Coordinates](Appendix%20C%20--%20Schema%20Coordinates.md)