Grammar

This issue tracks everything related to grammar.

* [ ] matrix-org/matrix-spec#174 - opaque IDs
* [ ] matrix-org/matrix-spec#290 - device IDs
* [ ] matrix-org/matrix-spec#503 - MXCs
* [ ] matrix-org/matrix-spec#593 - filter IDs
* [ ] matrix-org/matrix-spec#625 - access tokens
* [ ] https://github.com/matrix-org/matrix-spec/issues/1354 - signing key IDs
* [ ] matrix-org/matrix-spec#176 - aliases
* [ ] matrix-org/matrix-spec#175 - room IDs and event IDs
* [ ] https://github.com/matrix-org/matrix-spec/issues/278 - length limit
* [ ] matrix-org/matrix-spec#177 - disambiguation and display names
* [ ] matrix-org/matrix-spec#364 - tags
* [ ] https://github.com/matrix-org/matrix-spec/issues/1332 - historical user IDs
* [ ] https://github.com/matrix-org/matrix-spec/issues/2356
* [ ] https://github.com/matrix-org/matrix-spec/issues/2355

Start by reviewing the linked Matrix specification issues, beginning with the opaque IDs, aliases, room and event IDs, and display-name items listed here. Done would require resolving the relevant grammar checklist entries, but this issue does not define a narrower scope or identify files, tests, or a single acceptance criterion.

Written by the indexing model from the issue text.