another go at arbitrary keywords

Author: Phil Sturgeon

versions/3.1.0.md

@@ -2321,7 +2321,7 @@ The following properties are taken from the JSON Schema definition but their def
 
 Alternatively, any time a Schema Object can be used, a [Reference Object](#referenceObject) can be used in its place. This allows referencing definitions instead of defining them inline.
 
-In addition to the JSON Schema properties, the following OpenAPI vocabulary properties MAY be used for further schema documentation:
+In addition to the JSON Schema properties defined in the JSON Schema Core and JSON Schema Validation vocabularies, any properties can be used from any vocabularies, or entirely arbitrary keywords. OpenAPI has its own vocabulary properties which MAY be used for further schema description:
 
 ##### Fixed Fields
 
@@ -2335,8 +2335,6 @@ Field Name | Type | Description
 
 This object MAY be extended with [Specification Extensions](#specificationExtensions). 
 
-In previous versions of OpenAPI, Specification Extensions were the only way to add properties, but since v3.1.0 matches JSON Schema in allowing any properties to be used inside the Schema Object. These properties could be defined in their own vocabulary, or entirely arbitrary, and they do not need to follow any specific naming pattern or convention. 
-
 ###### <a name="schemaComposition"></a>Composition and Inheritance (Polymorphism)
 
 The OpenAPI Specification allows combining and extending model definitions using the `allOf` property of JSON Schema, in effect offering model composition.