Merge pull request #2032 from matrix-org/travis/1.0/redaction-effects

Clarify how redactions affect room state

changelogs/client_server/newsfragments/2032.clarification

@@ -0,0 +1 @@
+Clarify how redactions affect room state.

specification/client_server_api.rst

@@ -1534,6 +1534,16 @@ property of the redacted event, under the ``redacted_because`` key. When a
 client receives a redaction event it should change the redacted event in the
 same way a server does.
 
+.. NOTE::
+
+    Redacted events can still affect the state of the room. When redacted,
+    state events behave as though their properties were simply not specified,
+    except those protected by the redaction algorithm. For example,
+    a redacted ``join`` event will still result in the user being considered joined.
+    Similarly, a redacted topic does not necessarily cause the topic to revert to
+    what is was prior to the event - it causes the topic to be removed from the room.
+
+
 Events
 ++++++