Merge cc2623f8da into ef010cd408

Signed-off-by: Johannes Marbach <n0-0ne+github@mailbox.org>

changelogs/client_server/newsfragments/2304.clarification

@@ -0,0 +1 @@
+Clarify the requiredness of `event_id` in `predecessor`.

content/client-server-api/modules/room_upgrades.md

@@ -43,8 +43,8 @@ They must be explicitly set during the `/upgrade` call.
 {{% /boxes/note %}}
 
 {{% boxes/note %}}
-{{% added-in v="1.16" %}} When upgrading to room version 12 or later, the `predecessor` field MAY NOT contain
+{{% added-in v="1.16" %}} When upgrading to room version 12 or later, the `event_id` property inside
-an `event_id`.
+`predecessor` MAY be omitted.
 {{% /boxes/note %}}
 
 3.  Replicates transferable state events to the new room. The exact

content/rooms/fragments/v1-floaty-power-levels.md

@@ -5,8 +5,8 @@ When the value is a float
  * First, exponential notation is applied: `5.114698E4` becomes `51146.98`
  * Second, the value is truncated at the decimal point: `51146.98` becomes `51146`.
 
-Any float greater than or equal to `1e309` must result in the powerlevel event
+Values outside the range represented by IEE754 binary64 (a "double") cause the
-being rejected.
+powerlevel event to be rejected.
 
 For example, this is a valid `m.room.power_levels` event in this room version: