Take standards@ feedback into account

xep-0444.xml

@@ -75,6 +75,7 @@
   </p>
 </section1>
 <section1 topic='Discovering support' anchor='disco'>
+  <section2 topic="Basic support" anchor="disco-base">
     <p>
       If a client implements message reactions, it MUST specify the 
       'urn:xmpp:reactions:0' feature in its service discovery information features
@@ -98,6 +99,47 @@
 ...
   </query>
   </iq>]]></example>
+  </section2>
+  <section2 topic="Restricted reactions" anchor="disco-restricted">
+    <p>
+      In some cases, only a limited number and/or subset
+      of emojis are allowed to react to a message.
+      This is particularly useful in the context of gateways to other chat
+      networks that are not as permissive about which and how many emojis
+      can be used for message reactions.
+      MUC components may also allow room admins to restrict the subset and/or number
+      of emojis per message.
+    </p>
+    <p>
+      To allow clients to adapt their UIs, entities that have such restrictions in place
+      SHOULD advertise it with &xep0128; in a &xep0004; using the
+      'urn:xmpp:reactions:0:restrictions' namespace as FORM_TYPE.
+    </p>
+    <example caption='Entities advertises support for restricted reactions'><![CDATA[
+<iq type='result'
+    to='juliet@capulet.lit/balcony'
+    from='romeo@montague.lit/orchard'
+    id='info1'>
+  <query xmlns='http://jabber.org/protocol/disco#info'>
+  ...
+    <feature var='urn:xmpp:reactions:0'/>
+    <x xmlns='jabber:x:data' type='result'>
+      <field var='FORM_TYPE' type='hidden'>
+        <value>urn:xmpp:reactions:0:restrictions</value>
+      </field>
+      <field var='max_reactions_per_user'>
+        <value>1</value>
+      </field>
+      <field var='allowlist'>
+        <value>💘</value>
+        <value>❤️</value>
+        <value>💜</value>
+      </field>
+    </x> 
+  ...
+  </query>
+</iq>]]></example>
+  </section2>
 </section1>
 <section1 topic='Use Cases' anchor='usecases'>
   <section2 topic="Sending reactions to a message" anchor="sending-reactions">
@@ -146,15 +188,11 @@
   <store xmlns="urn:xmpp:hints"/>
 </message>]]></example>
   </section2>
-  <section2 topic="Rejecting a reaction" anchor="restricting-reactions">
+  <section2 topic="Rejecting a reaction" anchor="rejecting">
     <p>
-      In some cases, only a limited number and/or subset
-      of emojis are allowed to react to a message.
-      This is particularly useful in the context of gateways to other chat
-      networks that are not as permissive about which and how many emojis
-      can be used for message reactions.
-      MUC components may also allow room admins to restrict the subset and/or number
-      of emojis per message.
+      Entities implementing reaction restrictions MUST reply to invalid reactions payloads
+      with a message type="error" containing a 'not-acceptable' error.
+      The error payload SHOULD contain a human-readable text message explaining the reaction rules.
     </p>
     <example caption="Romeo sends a message"><![CDATA[
 <message from="romeo@legacy-love-network.capulet.net"
@@ -174,9 +212,6 @@
   </reactions>
   <store xmlns="urn:xmpp:hints"/>
 </message>]]></example>
-    <p>
-      In this case, the recipient (or any intermediary node) MUST reject the reaction-containing message.
-    </p>
     <example caption="Romeo rejects the reactions"><![CDATA[
 <message from="romeo@legacy-love-network.capulet.net"
         to="juliet@capulet.net"
@@ -191,27 +226,8 @@
   </error>
 </message>]]></example>
     <p>
-      When receiving this kind of error message, the reaction-sending entity MUST consider that its emoji reactions
-      to this message are now void.
-    </p>
-    <p>
-      Optionally, an error message can contain a reactions element, listing the subset of emojis that were valid in
-      the original reactions message.
-    </p>
-    <example caption="Romeo removes a subset of reactions"><![CDATA[
-<message from="romeo@legacy-love-network.capulet.net"
-        to="juliet@capulet.net"
-        type="error"
-        id="will-be-rejected1">
-  <error xmlns="jabber:client" type="modify">
-    <not-acceptable xmlns="urn:ietf:params:xml:ns:xmpp-stanzas" />
-    <reactions id='restricted-reactions-1' xmlns='urn:xmpp:reactions:0'>
-      <reaction>💘</reaction>
-    </reactions>
-  </error>
-</message>]]></example>
-    <p>
-      In this case, the reaction-sending entity MUST modify the emojis accordingly.
+      When receiving this error message, the reaction-sending entity MUST revert the "message reactions"
+      to its previous state in its user interface.
     </p>
   </section2>
 </section1>