Add rationale for Peer Trust Chain in the request

Author: selfissued

openid-federation-1_0.xml

@@ -1376,6 +1376,8 @@
 	  that the Entity at the beginning of the Trust Chain
 	  has in common with the audience of the JWT.
 	  Otherwise, the issuer is free to select the Trust Anchor to use.
+	 </t>
+	 <t>
           Most signed JWTs MAY include the
           <spanx style="verb">trust_chain</spanx> JWS header parameter,
           with a few exceptions.
@@ -1423,6 +1425,8 @@
 	    Inclusion of both Trust Chains enables achieving
 	    the Federation Integrity and Metadata Integrity properties,
 	    as defined in <xref target="App-Fed-Linkage"/>.
+	  </t>
+	  <t>
 	    Entity Configurations and Subordinate Statements MUST NOT
 	    contain the <spanx style="verb">peer_trust_chain</spanx> header parameter,
 	    as they are integral components of a Trust Chain.
@@ -7528,7 +7532,7 @@ HTTP/1.1 302 Found
         </t>
       </section>
 
-      <section title="Rationale for the Trust Chain in the Request" anchor="TrustChainParamRationale">
+      <section title="Rationale for Trust Chains in the Request" anchor="TrustChainRationale">
         <t>
           Both Automatic and Explicit Client Registration support
           the submission of the Trust Chain embedded in the Request,
@@ -7567,6 +7571,15 @@ HTTP/1.1 302 Found
 
 	  </list>
         </t>
+	<t>
+	  Both also support the submission of the Peer Trust Chain,
+	  which provides a Trust Chain between the OP
+	  and the Trust Anchor the RP selected.
+	  As described in <xref target="peer_trust_chain_head_param"/>,
+	  inclusion of both Trust Chains enables achieving
+	  the Federation Integrity and Metadata Integrity properties,
+	  as defined in <xref target="App-Fed-Linkage"/>.
+	</t>
       </section>
 
     </section>