From c578129bed5e342c0b322764676e073b7377f779 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?K=C3=A9vin=20Commaille?=
<76261501+zecakeh@users.noreply.github.com>
Date: Tue, 3 Feb 2026 17:35:58 +0100
Subject: [PATCH] Spec for MSC4313: Require HTML `
` `start` Attribute
support (#2299)
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
* Spec for MSC4313: Require HTML start Attribute support
Signed-off-by: Kévin Commaille
* Add changelog
Signed-off-by: Kévin Commaille
* Apply suggestion
Signed-off-by: Kévin Commaille
---------
Signed-off-by: Kévin Commaille
---
changelogs/client_server/newsfragments/2299.feature | 1 +
content/client-server-api/modules/instant_messaging.md | 4 ++++
2 files changed, 5 insertions(+)
create mode 100644 changelogs/client_server/newsfragments/2299.feature
diff --git a/changelogs/client_server/newsfragments/2299.feature b/changelogs/client_server/newsfragments/2299.feature
new file mode 100644
index 00000000..dc36c6db
--- /dev/null
+++ b/changelogs/client_server/newsfragments/2299.feature
@@ -0,0 +1 @@
+Clients supporting the `ol` HTML element must also support the `start` attribute, as per [MSC4313](https://github.com/matrix-org/matrix-spec-proposals/pull/4313).
diff --git a/content/client-server-api/modules/instant_messaging.md b/content/client-server-api/modules/instant_messaging.md
index 5c8a802c..a64baa25 100644
--- a/content/client-server-api/modules/instant_messaging.md
+++ b/content/client-server-api/modules/instant_messaging.md
@@ -84,6 +84,10 @@ Additionally, web clients should ensure that *all* `a` tags get a
`rel="noopener"` to prevent the target page from referencing the
client's tab/window.
+{{% added-in v="1.18" %}} Clients that support rendering numbered lists via the
+`ol` tag MUST also support the `start` attribute in order to prevent loss of
+meaning of a message due to the numbering of list items.
+
Tags must not be nested more than 100 levels deep. Clients should only
support the subset of tags they can render, falling back to other
representations of the tags where possible. For example, a client may