W3C home > Mailing lists > Public > public-tracking@w3.org > October 2011

exclude comma from DNT extension syntax

From: Roy T. Fielding <fielding@gbiv.com>
Date: Mon, 31 Oct 2011 16:35:35 -0700
Message-Id: <C1A8D068-3517-49CD-BEBD-B23215FA6B05@gbiv.com>
To: "public-tracking@w3.org Group WG" <public-tracking@w3.org>
Julian Reschke suggested online that comma should be excluded to
avoid confusion with header recombining in HTTP.  The following
change is now in the TPE spec.

....Roy

Index: tracking-dnt.html
===================================================================
RCS file: /w3ccvs/WWW/2011/tracking-protection/drafts/tracking-dnt.html,v
retrieving revision 1.28
retrieving revision 1.29
diff -u -r1.28 -r1.29
--- tracking-dnt.html	28 Oct 2011 09:22:26 -0000	1.28
+++ tracking-dnt.html	31 Oct 2011 23:11:47 -0000	1.29
@@ -281,7 +281,7 @@
         <pre class="abnf">
 DNT-field-name  = "DNT"                          ; case-insensitive
 DNT-field-value = ( "0" / "1" ) *DNT-extension   ; case-sensitive
-DNT-extension   = %x21-7E                        ; any visible ASCII
+DNT-extension   = %x21-2B / %x2D-7E              ; visible ASCII except ","
         </pre>
         <p>
           The DNT field-value sent by a user agent MUST begin with the
@@ -330,7 +330,10 @@
           as <q>DNT is enabled, but if you understand the refinements defined
           by x, y, or z, then adjust my preferences according to those
           refinements.</q>  Extensions can only transmitted if the user has
-          <a>enabled</a> DNT.
+          <a>enabled</a> DNT.  The extension syntax excludes the comma (",")
+          character in order to to differentiate valid field values from an
+          invalid occurrence of multiple DNT header fields that have been
+          combined as a single comma-separated list by a generic HTTP parser.
         </p>
         <p class="note">
           Designers of future extensions should note that, once enabled by
Received on Monday, 31 October 2011 23:36:06 UTC

This archive was generated by hypermail 2.3.1 : Friday, 3 November 2017 21:44:41 UTC