Add room version 11 (#1604)

* Remove duplicate words.

* Add information on room version 11.

* Note some event changes.

* Newsfragment

* Fix-up event schema.

* Apply suggestions from code review

Co-authored-by: Richard van der Hoff <1389908+richvdh@users.noreply.github.com>

* Fix 'new in this version'.

* Clarify creator field.

* Fix-up event format & examples.

* Move the Redactions section to the client section.

* Reference the sender instead of the creator.

* More links

* Even more links.

* Fix order of headers.

* Fix typos.

Co-authored-by: Richard van der Hoff <1389908+richvdh@users.noreply.github.com>

* Clarify description of creator.

Co-authored-by: Richard van der Hoff <1389908+richvdh@users.noreply.github.com>

* Clean-up intro paragraphs for redactions.

* Clean-up examples and language.

* Review comments.

* FIx-up markup tags.

---------

Co-authored-by: Richard van der Hoff <1389908+richvdh@users.noreply.github.com>

changelogs/room_versions/newsfragments/1604.feature

@@ -0,0 +1 @@
+Add room version 11 as per [MSC3820](https://github.com/matrix-org/matrix-spec-proposals/pull/3820).

content/rooms/_index.md

@@ -36,11 +36,11 @@ Alternatively, consider flipping the column/row organization to be features
 up top and versions on the left.
 -->
 
-| Feature \ Version | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 |
-|-------------------|---|---|---|---|---|---|---|---|---|----|
-| **Knocking**      | ❌ | ❌ | ❌ | ❌ | ❌ | ❌ | ✔ | ✔ | ✔ | ✔ |
-| **Restricted join rules** | ❌ | ❌ | ❌ | ❌ | ❌ | ❌ | ❌ | ✔ | ✔ | ✔ |
-| **`knock_restricted` join rule** | ❌ | ❌ | ❌ | ❌ | ❌ | ❌ | ❌ | ❌ | ❌ | ✔ |
+| Feature \ Version | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 |
+|-------------------|---|---|---|---|---|---|---|---|---|----|----|
+| **Knocking**      | ❌ | ❌ | ❌ | ❌ | ❌ | ❌ | ✔ | ✔ | ✔ | ✔ | ✔ |
+| **Restricted join rules** | ❌ | ❌ | ❌ | ❌ | ❌ | ❌ | ❌ | ✔ | ✔ | ✔ | ✔ |
+| **`knock_restricted` join rule** | ❌ | ❌ | ❌ | ❌ | ❌ | ❌ | ❌ | ❌ | ❌ | ✔ | ✔ |
 
 ## Complete list of room versions
 
@@ -57,8 +57,7 @@ the default room version when creating new rooms.
 
 The available room versions are:
 
--   [Version 1](/rooms/v1) - **Stable**. The current version of most
-    rooms.
+-   [Version 1](/rooms/v1) - **Stable**. The initial room version.
 -   [Version 2](/rooms/v2) - **Stable**. Implements State Resolution
     Version 2.
 -   [Version 3](/rooms/v3) - **Stable**. Introduces events whose IDs
@@ -76,6 +75,7 @@ The available room versions are:
     redacting some membership events.
 -   [Version 10](/rooms/v10) - **Stable**. Enforces integer-only power levels
     and adds `knock_restricted` join rule.
+-   [Version 11](/rooms/v11) - **Stable**. Clarifies the redaction algorithm.
 
 ## Room version grammar
 

content/rooms/fragments/v1-redactions.md

@@ -19,12 +19,14 @@ not in the following list:
 -   `membership`
 
 The content object must also be stripped of all keys, unless it is one
-of one of the following event types:
+of the following event types:
 
--   `m.room.member` allows key `membership`.
--   `m.room.create` allows key `creator`.
--   `m.room.join_rules` allows key `join_rule`.
--   `m.room.power_levels` allows keys `ban`, `events`, `events_default`,
-    `kick`, `redact`, `state_default`, `users`, `users_default`.
--   `m.room.aliases` allows key `aliases`.
--   `m.room.history_visibility` allows key `history_visibility`.
+-   [`m.room.member`](/client-server-api#mroommember) allows key `membership`.
+-   [`m.room.create`](/client-server-api#mroomcreate) allows key `creator`.
+-   [`m.room.join_rules`](/client-server-api#mroomjoin_rules) allows key `join_rule`.
+-   [`m.room.power_levels`](/client-server-api#mroompower_levels) allows keys
+    `ban`, `events`, `events_default`, `kick`, `redact`, `state_default`, `users`,
+    `users_default`.
+-   [`m.room.aliases`](/client-server-api#historical-events) allows key `aliases`.
+-   [`m.room.history_visibility`](/client-server-api#mroomhistory_visibility) allows
+    key `history_visibility`.

content/rooms/fragments/v11-event-format.md

@@ -0,0 +1,4 @@
+
+Events in rooms of this version have the following structure:
+
+{{% definition path="api/server-server/definitions/pdu_v11" %}}

content/rooms/fragments/v11-redactions.md

@@ -0,0 +1,30 @@
+
+Upon receipt of a redaction event, the server must strip off any keys
+not in the following list:
+
+-   `event_id`
+-   `type`
+-   `room_id`
+-   `sender`
+-   `state_key`
+-   `content`
+-   `hashes`
+-   `signatures`
+-   `depth`
+-   `prev_events`
+-   `auth_events`
+-   `origin_server_ts`
+
+The content object must also be stripped of all keys, unless it is one
+of the following event types:
+
+-   [`m.room.member`](/client-server-api#mroommember) allows keys `membership`, `join_authorised_via_users_server`.
+    Additionally, it allows the `signed` key of the `third_party_invite` key.
+-   [`m.room.create`](/client-server-api#mroomcreate) allows all keys.
+-   [`m.room.join_rules`](/client-server-api#mroomjoin_rules) allows keys `join_rule`, `allow`.
+-   [`m.room.power_levels`](/client-server-api#mroompower_levels) allows keys
+    `ban`, `events`, `events_default`, `invite`, `kick`, `redact`, `state_default`,
+    `users`, `users_default`.
+-   [`m.room.history_visibility`](/client-server-api#mroomhistory_visibility)
+    allows key `history_visibility`.
+-   [`m.room.redaction`](/client-server-api#mroomredaction) allows key `redacts`.

content/rooms/fragments/v6-redactions.md

@@ -19,11 +19,13 @@ not in the following list:
 -   `membership`
 
 The content object must also be stripped of all keys, unless it is one
-of one of the following event types:
+of the following event types:
 
--   `m.room.member` allows key `membership`.
--   `m.room.create` allows key `creator`.
--   `m.room.join_rules` allows key `join_rule`.
--   `m.room.power_levels` allows keys `ban`, `events`, `events_default`,
-    `kick`, `redact`, `state_default`, `users`, `users_default`.
--   `m.room.history_visibility` allows key `history_visibility`.
+-   [`m.room.member`](/client-server-api#mroommember) allows key `membership`.
+-   [`m.room.create`](/client-server-api#mroomcreate) allows key `creator`.
+-   [`m.room.join_rules`](/client-server-api#mroomjoin_rules) allows key `join_rule`.
+-   [`m.room.power_levels`](/client-server-api#mroompower_levels) allows keys
+    `ban`, `events`, `events_default`, `kick`, `redact`, `state_default`, `users`,
+    `users_default`.
+-   [`m.room.history_visibility`](/client-server-api#mroomhistory_visibility) allows
+    key `history_visibility`.

content/rooms/fragments/v9-redactions.md

@@ -1,24 +1,3 @@
----
----
-
-{{% added-in this=true %}} `m.room.member` events now keep `join_authorised_via_users_server`
-in addition to other keys in `content` when being redacted.
-
-{{% boxes/rationale %}}
-Without the `join_authorised_via_users_server` property, redacted join events
-can become invalid when verifying the auth chain of a given event, thus creating
-a split-brain scenario where the user is able to speak from one server's
-perspective but most others will continually reject their events.
-
-This can theoretically be worked around with a rejoin to the room, being careful
-not to use the faulty events as `prev_events`, though instead it is encouraged
-to use v9 rooms over v8 rooms to outright avoid the situation.
-
-[Issue #3373](https://github.com/matrix-org/matrix-doc/issues/3373) has further
-information.
-{{% /boxes/rationale %}}
-
-The full redaction algorithm follows.
 
 Upon receipt of a redaction event, the server must strip off any keys
 not in the following list:
@@ -40,11 +19,15 @@ not in the following list:
 -   `membership`
 
 The content object must also be stripped of all keys, unless it is one
-of one of the following event types:
-
--   `m.room.member` allows keys `membership`, `join_authorised_via_users_server`.
--   `m.room.create` allows key `creator`.
--   `m.room.join_rules` allows keys `join_rule`, `allow`.
--   `m.room.power_levels` allows keys `ban`, `events`, `events_default`,
-    `kick`, `redact`, `state_default`, `users`, `users_default`.
--   `m.room.history_visibility` allows key `history_visibility`.
+of the following event types:
+
+-   [`m.room.member`](/client-server-api#mroommember) allows keys `membership`,
+    `join_authorised_via_users_server`.
+-   [`m.room.create`](/client-server-api#mroomcreate) allows key `creator`.
+-   [`m.room.join_rules`](/client-server-api#mroomjoin_rules) allows keys `join_rule`,
+    `allow`.
+-   [`m.room.power_levels`](/client-server-api#mroompower_levels) allows keys
+    `ban`, `events`, `events_default`, `kick`, `redact`, `state_default`, `users`,
+    `users_default`.
+-   [`m.room.history_visibility`](/client-server-api#mroomhistory_visibility)
+    allows key `history_visibility`.