[mediaqueries-3] Mark normative errata as candidate change

Author: frivoal

mediaqueries-3/Overview.html

@@ -157,6 +157,8 @@ <h2 class="no-num no-toc" id=status>Status of this document</h2>
    W3C Patent Policy</a>.</p>
   <!--end-status-->
 
+  <div class="correction"><a href="https://www.w3.org/Consortium/Process/#candidate-correction">Candidate corrections</a> are marked in the document.</div>
+
   <nav id="toc">
   <h2 class="no-num no-toc" id=contents>Table of contents</h2>
   <!--begin-toc-->
@@ -560,18 +562,43 @@ <h3 id=error-handling><span class=secno>3.1. </span>Error Handling</h3>
   <p>For media queries that are not conforming user agents need to follow the
    rules described in this section.
 
+  <div class="correction" id="c1">
+   <span class="marker">Candidate Correction 1:</span>
+   Clarify that the keywords ‘<code>not</code>’, ‘<code>and</code>’, ‘<code>only</code>’, and ‘<code>or</code>’ should not be treated as unknown media types,
+   but as syntax errors when used in place of media types.
+
+   <p>The reasoning for this change can be found in <a href="https://lists.w3.org/Archives/Public/www-style/2013May/0783.html">the minutes of the 2013-05-30 CSS WG teleconference</a>
+   and in the emails referenced therefrom.
+   <details>
+    <summary>This change has tests</summary>
+    <a href="https://github.com/web-platform-tests/wpt/commit/ea1821d4bd24ed1e859db03571cca8e783dbf957">Tests for this change</a> have been added to <abbr title="Web Platform Tests">WPT</abbr>.
+    The results can be viewed at <a href="https://wpt.fyi/results/css/mediaqueries?q=mq-invalid-media-type">wpt.fyi</a>.
+   </details>
+  </div>
+
   <ul>
    <li>
     <p><strong>Unknown media types.</strong> Unknown media types evaluate to
      false. Effectively, they are treated identically to known media types
-     that do not match the media type of the device.</p>
+     that do not match the media type of the device.
+     <ins cite="#c1">However, an exception is made for media types ‘<code>not</code>’, ‘<code>and</code>’, ‘<code>only</code>’, and ‘<code>or</code>’.
+     Even though they do match the IDENT production,
+     they must not be treated as unknown media types,
+     but rather trigger the malformed query clause.</ins></p>
 
     <div class=example>
      <p>The media query "<code>unknown</code>" will evaluate to false, unless
       <code>unknown</code> is actually a supported media type. Similarly,
       "<code>not unknown</code>" will evaluate to true.</p>
     </div>
 
+    <ins cite="#c1">
+    <div class="example">
+     <p>The following is a malformed media query because it uses ‘<code>only</code>’ and ‘<code>or</code>’ as media types.</p>
+     <pre><code>@media only and or { … }</code></pre>
+    </div>
+    </ins>
+
     <p class=note>Unknown media types are distinct from media types that do
      not actually match the IDENT production. Those fall under the malformed
      media query clause.</p>
@@ -1104,7 +1131,15 @@ <h2 id=changes><span class=secno>7. </span>Changes</h2>
   <h3 id=changes-2012><span class=secno>7.1. </span>Changes Since the 19 June 2012
    Recommendation</h3>
 
-  <p>A handful of editorial and markup corrections were made:
+  <p>Candidate Corrections were introduced:
+  <ul>
+   <li><a href="#c1">Candidate Change 1</a> in <a href="#error-handling">Section 3.1</a>:
+    Clarify that the keywords ‘<code>not</code>’, ‘<code>and</code>’, ‘<code>only</code>’, and ‘<code>or</code>’ should not be treated as unknown media types,
+    but as syntax errors when used in place of media types.
+
+  </ul>
+
+  <p>A handful of editorial and markup corrections were also made:
 
   <ul>
    <li><a href="#media0">Section 2</a>: Dropped a redundant attribute in an example.
@@ -1270,4 +1305,4 @@ <h3 class=no-num id=other-references>Other references</h3>
    <!---->
   </dl>
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+<script src="https://www.w3.org/scripts/TR/2021/fixup.js"></script>