Alternative wording

Author: benjie

spec/Section 3 -- Type System.md

@@ -211,15 +211,19 @@ type MyMutationRootType {
 
 **Default Root Operation Type Names**
 
-While any type can be the root operation type for a GraphQL operation, the type
-system definition language can omit the schema definition when each of the
-{`query`}, {`mutation`}, and {`subscription`} root types are named {"Query"},
-{"Mutation"}, and {"Subscription"} respectively (if present), and these names
-are only used for root types.
+:: While any type can be the root operation type for a GraphQL operation, the
+_default root operation type name_ for the {`query`}, {`mutation`}, and
+{`subscription`} root types are {"Query"}, {"Mutation"}, and {"Subscription"}
+respectively.
+
+The type system definition language can omit the schema definition when each
+root type present uses its respective _default root operation type name_ and no
+other type uses a default root operation type name.
 
 Likewise, when representing a GraphQL schema using the type system definition
-language, a schema definition should be omitted if it only uses these default
-root operation type names as the names of the respective root types.
+language, a schema definition should be omitted if each root type present uses
+its respective _default root operation type name_ and no other type uses a
+default root operation type name.
 
 This example describes a valid complete GraphQL schema, despite not explicitly
 including a {`schema`} definition. The {"Query"} type is presumed to be the