# Matrix Specification Changes since last release


## Client-Server API

**Backwards Compatible Changes**

- [ ] Specify `unsigned.replaces_state` in client-formatted events. Contributed by @nexy7574. ([#2345](https://github.com/matrix-org/matrix-spec/issues/2345))
- [ ] Specify `m.key_backup` account data, as per [MSC4287](https://github.com/matrix-org/matrix-spec-proposals/pull/4287). ([#2354](https://github.com/matrix-org/matrix-spec/issues/2354))
- [ ] Specify the `mutual_rooms` API to get rooms in common with another user, as per
  [MSC2666](https://github.com/matrix-org/matrix-spec-proposals/pull/2666). ([#2367](https://github.com/matrix-org/matrix-spec/issues/2367))

**Spec Clarifications**

- [ ] Clarify SAS commitment calculation for `m.key.verification.accept` messages. ([#2344](https://github.com/matrix-org/matrix-spec/issues/2344))
- [ ] Clarify formats of string types. ([#2347](https://github.com/matrix-org/matrix-spec/issues/2347), [#2349](https://github.com/matrix-org/matrix-spec/issues/2349), [#2358](https://github.com/matrix-org/matrix-spec/issues/2358), [#2359](https://github.com/matrix-org/matrix-spec/issues/2359))
- [ ] Fix ordering of common error codes. ([#2348](https://github.com/matrix-org/matrix-spec/issues/2348))
- [ ] Clarify how to find `via` parameter when following room upgrades. ([#2352](https://github.com/matrix-org/matrix-spec/issues/2352))


## Server-Server API

**Spec Clarifications**

- [ ] Clarify the behaviour and response format of `GET /_matrix/federation/v1/query/profile`. ([#2326](https://github.com/matrix-org/matrix-spec/issues/2326))
- [ ] Clarify how multiple signatures should be handled during signature verification. Contributed by @nexy7574. ([#2341](https://github.com/matrix-org/matrix-spec/issues/2341))


## Application Service API

No significant changes.


## Identity Service API

No significant changes.


## Push Gateway API

No significant changes.


## Room Versions

No significant changes.


## Olm & Megolm

**Spec Clarifications**

- [ ] Update links to Olm in the Megolm section to point to the Matrix spec. ([#2361](https://github.com/matrix-org/matrix-spec/issues/2361))
- [ ] Fix various typos throughout the specification. ([#2369](https://github.com/matrix-org/matrix-spec/issues/2369))


## Appendices

**Spec Clarifications**

- [ ] Fix various typos throughout the specification. ([#2369](https://github.com/matrix-org/matrix-spec/issues/2369))


## Internal Changes/Tooling

**Spec Clarifications**

- [ ] Update and fix GitHub Actions. ([#2343](https://github.com/matrix-org/matrix-spec/issues/2343), [#2369](https://github.com/matrix-org/matrix-spec/issues/2369))
- [ ] Upgrade Docsy theme to v0.14.3. ([#2346](https://github.com/matrix-org/matrix-spec/issues/2346))
- [ ] Configure a new changelog section for the Olm & Megolm specs. ([#2364](https://github.com/matrix-org/matrix-spec/issues/2364))
- [ ] Clarify use of UK vs US English in documentation style doc. ([#2366](https://github.com/matrix-org/matrix-spec/issues/2366))