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Co-authored-by: Benjie <[email protected]>

Author: Shane32

spec/Section 5 -- Validation.md

@@ -332,20 +332,20 @@ contain any number of operations, each of which may contain different root
 fields. When executed, a document containing multiple subscription operations
 must provide the operation name as described in {GetOperation()}.
 
-### Operation Type Configuration
+### Operation Type Exists
 
 #### Formal Specification
 
 For each operation definition in the document:
 
-- Let {operationType} be the type of the operation (query, mutation, or subscription).
-- The corresponding type for {operationType} must be defined in the schema.
+- Let {operationType} be the type of the operation (`query`, `mutation`, or `subscription`).
+- The corresponding _root operation type_ for {operationType} must be defined in the schema.
 
 #### Explanatory Text
 
-The schema must be properly configured to handle mutation and subscription operation
-types. This ensures that when a mutation or subscription operation is defined in the
-document, the schema includes the appropriate type to handle these operations.
+A schema defines the root operation types that it supports. Any document that
+contains an operation of a type unsupported by the schema is invalid, since such
+an operation cannot be executed.
 
 While query operations are required for all schemas, mutation and subscription operations
 are optional. If the schema does not include the necessary type for a mutation or subscription
@@ -354,7 +354,7 @@ operation defined in the document, it will be considered invalid.
 For example, the following document is valid if the schema includes a Mutation type, but
 invalid if it does not:
 
-```graphql
+```graphql example
 mutation {
   likeStory(storyID: 12345) {
     story {