From 2e8f05adfdcd3fdd06c35458479e48285a4fb542 Mon Sep 17 00:00:00 2001
From: Jeffrey Yasskin <jyasskin@google.com>
Date: Sun, 24 Nov 2024 21:57:17 -0800
Subject: [PATCH] Warn about other notions of ASCII whitespace

---
 infra.bs | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/infra.bs b/infra.bs
index c0f79bc..a9e2da3 100644
--- a/infra.bs
+++ b/infra.bs
@@ -933,6 +933,20 @@ SPACE.
 
 <p class=note>"Whitespace" is a mass noun.
 
+<div class=note>
+ <p>The XML, JSON, and parts of the HTTP specifications exclude U+000C FF in their definition of
+ whitespace:
+
+ <ul class=brief>
+  <li>[[xml10#NT-S|XML's S production]]
+  <li>[[JSON#section-2|JSON's ws production]]
+  <li>[=HTTP whitespace=]
+ </ul>
+
+ <p>Prefer using Infra's [=ASCII whitespace=] definition for new features, unless your specification
+ deals exclusively with XML/JSON/HTTP.
+</div>
+
 <p>A <dfn export>C0 control</dfn> is a <a>code point</a> in the range U+0000 NULL to
 U+001F INFORMATION SEPARATOR ONE, inclusive.