Placeholder for extensible events power levels

proposals/3842-power-levels-message-events.md

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+# MSC3842: Power levels on message (extensible) events
+
+Currently in Matrix anyone can send an event of any type in most rooms, though some rooms (like
+announcement-only) rooms limit what some people can send. It's additionally been desirable to
+be able to ban images or other rich media in a room which might be bridged to a less capable
+platform, though this use-case is less common.
+
+This proposal aims to try and figure out power levels for events from the perspective of
+[MSC1767 Extensible Events](https://github.com/matrix-org/matrix-spec-proposals/pull/1767)
+where the client might end up rendering the event as a fallback rather than as the primary,
+easily-blocked, type. Similar considerations can be made for when the event type is hidden
+from the server, like with encrypted events.
+
+## Proposal
+
+TBD. I think we can rely on client-side enforcement when the event contains a mixed type? Power
+levels would no longer be used to enforce conversation norms and instead be used to encourage
+use cases like announcement rooms.
+
+## Potential issues
+
+TBD
+
+## Alternatives
+
+TBD
+
+## Security considerations
+
+TBD
+
+## Unstable prefix
+
+Not yet applicable.
+
+## Dependencies
+
+Soft dependencies:
+
+* [MSC1767: Extensible events](https://github.com/matrix-org/matrix-spec-proposals/pull/1767)