From 9d3871b2ede396eaa337a60f2abe7480d4328642 Mon Sep 17 00:00:00 2001
From: Frank Tang <ftang@chromium.org>
Date: Thu, 14 Dec 2023 15:09:21 -0800
Subject: [PATCH] Canonicalize value of extension in ApplyUnicodeExtensionToTag

Close #707
---
 spec/locale.html | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/spec/locale.html b/spec/locale.html
index 4e977e71..21bee558 100644
--- a/spec/locale.html
+++ b/spec/locale.html
@@ -136,7 +136,8 @@ <h1>
           1. Let _optionsValue_ be _options_.[[&lt;_key_&gt;]].
           1. If _optionsValue_ is not *undefined*, then
             1. Assert: Type(_optionsValue_) is String.
-            1. Set _value_ to _optionsValue_.
+            1. Let _optionsUValue_ be the ASCII-lowercase of _optionsValue_.
+            1. Set _value_ to the String value resulting from canonicalizing _optionsUValue_ as a value of key _key_ per <a href="https://unicode.org/reports/tr35/#processing-localeids">Unicode Technical Standard #35 Part 1 Core, Annex C LocaleId Canonicalization Section 5 Canonicalizing Syntax, Processing LocaleIds</a>.
             1. If _entry_ is not ~empty~, then
               1. Set _entry_.[[Value]] to _value_.
             1. Else,