From 4a267c8eaaa8505d8868b49efd31ffec8d4622a1 Mon Sep 17 00:00:00 2001 From: Adam Argyle Date: Wed, 17 Jan 2024 11:24:16 -0800 Subject: [PATCH] [css-media-5] fixes #9475 - prefers reduced data tag question --- mediaqueries-5/Overview.bs | 28 +++++++++++++++++----------- 1 file changed, 17 insertions(+), 11 deletions(-) diff --git a/mediaqueries-5/Overview.bs b/mediaqueries-5/Overview.bs index 44bede21078..055540d4057 100644 --- a/mediaqueries-5/Overview.bs +++ b/mediaqueries-5/Overview.bs @@ -3085,11 +3085,6 @@ Detecting the desire for light or dark color schemes: the 'prefers-color-scheme'

Detecting the desire for reduced data usage when loading a page: the 'prefers-reduced-data' feature

- Issue(4832): This feature may be an undesired source of fingerprinting, - with a bias towards low income with limited data. - A Privacy and Security section should be added to this spec, - and it should address this concern. - 
 	Name: prefers-reduced-data
 	Value: no-preference | reduce
@@ -3116,12 +3111,23 @@ Detecting the desire for reduced data usage when loading a page: the 'prefers-re
 
 	The method by which the user expresses their preference can vary.
 	It might be a system-wide setting exposed by the Operating System,
-	or a setting controlled by the user agent.
-
-	Note: User agents may consider setting this based on the same user
-	or system preference as they use to set the
-	Save-Data HTTP request
-	header.
+	or a setting controlled by the user agent. User agents may consider 
+	setting this based on the same user or system preference as they use to 
+	set the Save-Data 
+	HTTP request header.
+
+	Note: User agents should use their own user centered discretion when 
+	handling a toggle of this value, whether it's toggled post page load 
+	or during page load. A primary goal could be to not download unnecessary 
+	data. Consider, if a page is already loaded with high quality assets and 
+	the user changes their preference to reduced, the page should perhaps 
+	not update the document right away, instead wait for an explicit page 
+	reload invocation from the user. Consider also, if a page is taking a 
+	long time to download and a user changes their preference to reduced, 
+	this could be a nice point to save the user's bandwidth and immediately 
+	switch to downloading smaller assets. User agents should be free to 
+	implement logic as they see appropriate for situations like these, and 
+	also be aware the situations exist.
 
 	

 		For example, a site could honour the preference of a user who