hixie: Change how vendor extensions are marked up. (whatwg r5562)

hixie: Change how vendor extensions are marked up. (whatwg r5562)

http://dev.w3.org/cvsweb/html5/spec/Overview.html?r1=1.4443&r2=1.4444&f=h
http://html5.org/tools/web-apps-tracker?from=5561&to=5562

===================================================================
RCS file: /sources/public/html5/spec/Overview.html,v
retrieving revision 1.4443
retrieving revision 1.4444
diff -u -d -r1.4443 -r1.4444
--- Overview.html	29 Sep 2010 22:28:06 -0000	1.4443
+++ Overview.html	29 Sep 2010 22:38:20 -0000	1.4444
@@ -2890,13 +2890,13 @@
 
   <p>For markup-level features that are intended for use with
   <a href="#syntax">the HTML syntax</a>, extensions should be limited to new
-  attributes of the form "<code title=""><var title="">vendor</var>--<var title="">feature</var></code>", where
+  attributes of the form "<code title="">x0<var title="">vendor</var>-<var title="">feature</var></code>", where
   <var title="">vendor</var> is a short string that identifies the
-  vendor responsible for the extension, and <var title="">feature</var> is the name of the feature. (Note the use of
-  <em>two</em> hyphens in the name.) New element names should not be
-  created. Using attributes for such extensions exclusively allows
-  extensions from multiple vendors to co-exist on the same element,
-  which would not be possible with elements. Using the "<code title=""><var title="">vendor</var>--<var title="">feature</var></code>" form allows extensions to be made
+  vendor responsible for the extension, and <var title="">feature</var> is the name of the feature. New element names
+  should not be created. Using attributes for such extensions
+  exclusively allows extensions from multiple vendors to co-exist on
+  the same element, which would not be possible with elements. Using
+  the "<code title="">x-<var title="">vendor</var>-<var title="">feature</var></code>" form allows extensions to be made
   without risk of conflicting with future additions to the
   specification.</p>
 
@@ -2909,14 +2909,16 @@
    these features could write:</p>
 
    <pre>&lt;p&gt;This smells of lemons!
-&lt;span ferret--smellovision ferret--smellcode="LEM01"
-      mb--outputsmell mb--smell="lemon juice"&gt;&lt;/span&gt;&lt;/p&gt;</pre>
+&lt;span x-ferret-smellovision x-ferret-smellcode="LEM01"
+      x-mb-outputsmell x-mb-smell="lemon juice"&gt;&lt;/span&gt;&lt;/p&gt;</pre>
 
   </div>
 
-  <p>Attribute names containing two consecutive U+002D HYPHEN-MINUS
-  (-) characters are reserved for user agent use and are guaranteed to
-  never be formally added to the HTML language.</p>
+  <p>Attribute names beginning with the two characters "<code title="">x-</code>" are reserved for user agent use and are
+  guaranteed to never be formally added to the HTML language. For
+  flexibility, attributes names containing underscores (the U+005F LOW
+  LINE character) are also reserved for experimental purposes and are
+  guaranteed to never be formally added to the HTML language.</p>
 
   <p class="note">Pages that use such attributes are by definition
   non-conforming.</p>
@@ -2942,6 +2944,11 @@
 
   </div>
 
+  <p>When adding new <a href="#reflect" title="reflect">reflecting</a> IDL
+  attributes corresponding to content attributes of the form "<code title="">x-<var title="">vendor</var>-<var title="">feature</var></code>", the IDL attribute should be named
+  "<code title=""><var title="">vendor</var><var title="">Feature</var></code>" (i.e. the "<code title="">x</code>"
+  is dropped from the IDL attribute's name).</p>
+
   <hr><p>When vendor-neutral extensions to this specification are needed,
   either this specification can be updated accordingly, or an
   extension specification can be written that overrides the