Clarify what happens when there is no power_levels event

api/client-server/create_room.yaml

@@ -37,6 +37,9 @@ paths:
         the new room, including checking power levels for each event. It MUST
         apply the events implied by the request in the following order:
 
+        0. A default ``m.room.power_levels`` event, giving the room creator
+           (and not other members) permission to send state events.
+        
         1. Events set by ``presets``.
 
         2. Events listed in ``initial_state``, in the order that they are

event-schemas/schema/m.room.power_levels

@@ -29,6 +29,17 @@ description: |-
   to 50 if they are not specified in the ``m.room.power_levels`` event, or if
   the room contains no ``m.room.power_levels`` event.
 
+  .. NOTE::
+
+    As noted above, in the absence of an ``m.room.power_levels`` event, the
+    ``state_default`` is 0, and all users are considered to have power level 0.
+    That means that **any** member of the room can send an
+    ``m.room.power_levels`` event, changing the permissions in the room.
+
+    Server implementations should therefore ensure that each room has an
+    ``m.room.power_levels`` event as soon as it is created. See also the
+    documentation of the ``/createRoom`` API.
+
 properties:
   content:
     properties:

templating/matrix_templates/templates/events.tmpl

@@ -9,7 +9,8 @@
 
 {% endif -%}
 
-{{event.desc | wrap(80)}}
+{{event.desc}}
+
 {% for table in event.content_fields %}
 {{"``"+table.title+"``" if table.title else "" }}