Merge pull request #3152 from w3c/wcag-2.1-2.0-parsing-note

Adding Parsing notes from meeting

Author: alastc

guidelines/sc/20/parsing.html

@@ -10,9 +10,14 @@ Parsing
       these features.
    p>
 
-   <p class="note">Start and end tags that are missing a critical character in their formation, such
-      as a closing angle bracket or a mismatched attribute value quotation mark are not
-      complete.
-   p>
+   <p class="note">This Success Criterion should be considered as always satisfied for any content using HTML or XML.p>
+
+   <div class="note">
+      <p>Since this criterion was written, the HTML Standard has adopted specific requirements governing how user agents must handle incomplete tags, incorrect element nesting, duplicate attributes, and non-unique IDs.p>
+      
+      <p>Although the HTML Standard treats some of these cases as non-conforming for authors, it is considered to "allow these features" for the purposes of this Success Criterion because the specification requires that user agents support handling these cases consistently. In practice, this criterion no longer provides any benefit to people with disabilities in itself.p>
+      
+      <p>Issues such as missing roles due to inappropriately nested elements or incorrect states or names due to a duplicate ID are covered by different Success Criteria and should be reported under those criteria rather than as issues with 4.1.1.p>
+   div>
 
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