Latest updates to works in progress from feedback

Author: handrews

work-in-progress/WIP-jsonschema-core.html

@@ -653,7 +653,7 @@ <h1 id="rfc.section.7"><a href="#rfc.section.7">7.</a> The "$schema" keyword</h1
 <p id="rfc.section.7.p.2">The value of this keyword MUST be a <a href="#RFC3986">URI</a> <cite title="NONE">[RFC3986]</cite> (containing a scheme) and this URI MUST be normalized.  The current schema MUST be valid against the meta-schema identified by this URI.  </p>
 <p id="rfc.section.7.p.3">If this URI identifies a retrievable resource, that resource SHOULD be of media type "application/schema+json".  </p>
 <p id="rfc.section.7.p.4">The "$schema" keyword SHOULD be used in a root schema.  It MUST NOT appear in subschemas.  </p>
-<p><a id="CREF1" class="info">[CREF1]<span class="info">While this pattern is likely to remain best practice for schema authoring, implementation behavior is subject to be revised or liberalized in future drafts.  </span></a> </p>
+<p><a id="CREF1" class="info">[CREF1]<span class="info">Using multiple "$schema" keywords in the same document would imply that the vocabulary and therefore behavior can change within a document.  This would necessitate resolving a number of implementation concerns that have not yet been clearly defined.  So, while the pattern of using "$schema" only in root schemas is likely to remain the best practice for schema authoring, implementation behavior is subject to be revised or liberalized in future drafts.  </span></a> </p>
 <p id="rfc.section.7.p.6">Values for this property are defined in other documents and by other parties.  JSON Schema implementations SHOULD implement support for current and previous published drafts of JSON Schema vocabularies as deemed reasonable.  </p>
 <h1 id="rfc.section.8"><a href="#rfc.section.8">8.</a> Schema references with "$ref"</h1>
 <p id="rfc.section.8.p.1">The "$ref" keyword is used to reference a schema, and provides the ability to validate recursive structures through self-reference.  </p>