Using non-interoperable JSON may result in unpredictable metadata and…

… metadata policies (iss openid#35)

openid-federation-1_0.xml

@@ -2041,6 +2041,12 @@
                 An operator MUST NOT output a metadata parameter with the
                 <spanx style="verb">null</spanx> value.
               </t>
+              <t>
+                Metadata parameters and policies that conform to the JSON
+                grammar but are not interoperable uses of JSON, as per Sections
+                4 and 8 of <xref target="RFC8259"/>, may cause unpredictable
+                behavior.
+              </t>
 
             </list>
           </t>
@@ -8640,6 +8646,7 @@ HTTP/1.1 302 Found
       <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.7591.xml"/>
       <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.7638.xml"/>
       <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.8174.xml"/>
+      <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.8259.xml"/>
       <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.8414.xml"/>
       <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.8705.xml"/>
       <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.9101.xml"/>
@@ -10057,6 +10064,11 @@ Host: op.umu.se
 	    in the Explicit Registration response to be the Immediate Superior
 	    of the RP in the Trust Chain selected for it by the OP.
 	  </t>
+	  <t>
+	    Fixed #35: Clarified that using non-interoperable JSON, as per sections
+        4 and 8 of RFC 8259, may result in unpredictable metadata and metadata
+        policy behavior.
+	  </t>
 	</list>
       </t>