removed sectioning root concept

general clean up and closer alignment with @annevk PR whatwg#3499

source

@@ -2084,6 +2084,10 @@ a.setAttribute('href', 'https://example.com/'); // change the content attribute
     <p>Applications and tools that process HTML and XML documents for reasons other than to either
     render the documents or check them for conformance should act in accordance with the semantics
     of the documents that they process.</p>
+
+	<p class="example">A tool that generates document outlines but increases the nesting level for
+    each paragraph and does not increase the nesting level for <span
+    data-x="concept-heading">headings</span> would not be conforming.</p>
    </dd>
 
 
@@ -11159,17 +11163,12 @@ console.assert(image.height === 200);</code></pre>
    <li><code>section</code></li>
   </ul>
 
-  <p>Each <span>sectioning content</span> element potentially has a heading and an
-  <span>outline</span>. See the section on <span>headings and sections</span> for further
-  details.</p>
-
-  <p class="note">There are also certain elements that are <span data-x="sectioning root">sectioning
-  roots</span>. These are distinct from <span>sectioning content</span>.</p>
+  <p>See the section on <span>headings and sections</span> for further details.</p>
 
 
   <h6>Heading content</h6>
 
-  <p><dfn export>Heading content</dfn> defines the header of a section (whether explicitly marked
+  <p><dfn export>Heading content</dfn> defines the heading of a section (whether explicitly marked
   up using <span>sectioning content</span> elements, or implied by the heading content itself).</p>
 
   <!-- when updating this also update the category index -->
@@ -16248,7 +16247,7 @@ console.log(style.disabled); // false</code></pre>
 
   <dl class="element">
    <dt><span data-x="concept-element-categories">Categories</span>:</dt>
-   <dd><span>Sectioning root</span>.</dd>
+   <dd>None.</dd>
    <dt><span data-x="concept-element-contexts">Contexts in which this element can be used</span>:</dt>
    <dd>As the second element in an <code>html</code> element.</dd>
    <dt><span data-x="concept-element-content-model">Content model</span>:</dt>
@@ -17127,7 +17126,7 @@ interface <dfn interface>HTMLHeadingElement</dfn> : <span>HTMLElement</span> {
    <dd><span>Global attributes</span></dd>
    <dt><span
    data-x="concept-element-accessibility-considerations">Accessibility considerations</span>:</dt>
-   <dd>If the nearest ancestor <span>sectioning content</span> or <span>sectioning root</span>
+   <dd>If the nearest ancestor <span>sectioning content</span>
    element is <span>the body element</span>: <a
    href="https://w3c.github.io/html-aria/#el-header">for authors</a>; <a
    href="https://w3c.github.io/html-aam/#el-header-ancestorbody">for implementers</a>.</dd>
@@ -17181,8 +17180,7 @@ interface <dfn interface>HTMLHeadingElement</dfn> : <span>HTMLElement</span> {
   <p>In this example, the page has a page heading given by the <code>h1</code> element, and two
   subsections whose headings are given by <code>h2</code> elements. The content after the
   <code>header</code> element is still part of the last subsection started in the
-  <code>header</code> element, because the <code>header</code> element doesn't take part in the
-  <span>outline</span> algorithm.</p>
+  <code>header</code> element.</p>
 
    <pre><code class="html">&lt;body>
  &lt;header>
@@ -17223,7 +17221,7 @@ interface <dfn interface>HTMLHeadingElement</dfn> : <span>HTMLElement</span> {
    <dd><span>Global attributes</span></dd>
    <dt><span
    data-x="concept-element-accessibility-considerations">Accessibility considerations</span>:</dt>
-   <dd>If the nearest ancestor <span>sectioning content</span> or <span>sectioning root</span>
+   <dd>If the nearest ancestor <span>sectioning content</span>
    element is <span>the body element</span>: <a
    href="https://w3c.github.io/html-aria/#el-footer">for authors</a>; <a
    href="https://w3c.github.io/html-aam/#el-footer-ancestorbody">for implementers</a>.</dd>
@@ -17235,7 +17233,7 @@ interface <dfn interface>HTMLHeadingElement</dfn> : <span>HTMLElement</span> {
   </dl>
 
   <p>The <code>footer</code> element <span>represents</span> a footer for its nearest ancestor
-  <span>sectioning content</span> or <span>sectioning root</span> element. A footer typically
+  <span>sectioning content</span> element. A footer typically
   contains information about its section such as who wrote it, links to related documents, copyright
   data, and the like.</p>
 
@@ -17253,7 +17251,7 @@ interface <dfn interface>HTMLHeadingElement</dfn> : <span>HTMLElement</span> {
   <p>Footers don't necessarily have to appear at the <em>end</em> of a section, though they usually
   do.</p>
 
-  <p>When the nearest ancestor <span>sectioning content</span> or <span>sectioning root</span>
+  <p>When the nearest ancestor <span>sectioning content</span>
   element is <span>the body element</span>, then it applies to the whole page.</p>
 
   <p class="note">The <code>footer</code> element is not <span>sectioning content</span>; it doesn't
@@ -17794,7 +17792,7 @@ interface <dfn interface>HTMLHeadingElement</dfn> : <span>HTMLElement</span> {
 
     <tr>
      <td rowspan=2><code>h1</code>&ndash;<code>h6</code>
-     <td>A section heading
+     <td>A heading
     <tr>
      <td><pre class="example"><code class="html"><strong>&lt;h1></strong>The Guide To Music On The Playa<strong>&lt;/h1></strong>
 <strong>&lt;h2></strong>The Main Stage<strong>&lt;/h2></strong>
@@ -17808,19 +17806,19 @@ interface <dfn interface>HTMLHeadingElement</dfn> : <span>HTMLElement</span> {
     <tr>
      <td><pre class="example"><code class="html"><strong>&lt;hgroup></strong>
  &lt;h1>Burning Music&lt;/h1>
- &lt;h2>The Guide To Music On The Playa&lt;/h2>
+ &lt;p>The Guide To Music On The Playa&lt;/p>
 <strong>&lt;/hgroup></strong>
 &lt;section>
  <strong>&lt;hgroup></strong>
   &lt;h1>Main Stage&lt;/h1>
-  &lt;h2>The Fiction Of A Music Festival&lt;/h2>
+  &lt;p>The Fiction Of A Music Festival&lt;/p>
  <strong>&lt;/hgroup></strong>
  &lt;p>If you want to play on a stage, you <!--non-normative-->should bring one.&lt;/p>
 &lt;/section>
 &lt;section>
  <strong>&lt;hgroup></strong>
   &lt;h1>Loudness!&lt;/h1>
-  &lt;h2>Questions About Amplified Music&lt;/h2>
+  &lt;p>Questions About Amplified Music&lt;/p>
  <strong>&lt;/hgroup></strong>
  &lt;p>Amplifiers up to 300W or 90dB are welcome.&lt;/p>
 &lt;/section></code></pre>
@@ -18129,10 +18127,6 @@ of Gralmond's winters.&lt;/p></code></pre>
 
   </div>
 
-  <p class="note">The <code>hr</code> element does not affect the document's
-  <span>outline</span>.</p>
-
-
   <h4>The <dfn element><code>pre</code></dfn> element</h4>
 
   <dl class="element">
@@ -18257,7 +18251,6 @@ a friend lost to the
   <dl class="element">
    <dt><span data-x="concept-element-categories">Categories</span>:</dt>
    <dd><span>Flow content</span>.</dd>
-   <dd><span>Sectioning root</span>.</dd>
    <dd><span>Palpable content</span>.</dd>
    <dt><span data-x="concept-element-contexts">Contexts in which this element can be used</span>:</dt>
    <dd>Where <span>flow content</span> is expected.</dd>
@@ -19316,7 +19309,6 @@ first matching case):&lt;/p&gt;
   <dl class="element">
    <dt><span data-x="concept-element-categories">Categories</span>:</dt>
    <dd><span>Flow content</span>.</dd>
-   <dd><span>Sectioning root</span>.</dd>
    <dd><span>Palpable content</span>.</dd>
    <dt><span data-x="concept-element-contexts">Contexts in which this element can be used</span>:</dt>
    <dd>Where <span>flow content</span> is expected.</dd>
@@ -41293,7 +41285,6 @@ interface <dfn interface>HTMLTableRowElement</dfn> : <span>HTMLElement</span> {
 
   <dl class="element">
    <dt><span data-x="concept-element-categories">Categories</span>:</dt>
-   <dd><span>Sectioning root</span>.</dd>
    <dt><span data-x="concept-element-contexts">Contexts in which this element can be used</span>:</dt>
    <dd>As a child of a <code>tr</code> element.</dd>
    <dt><span data-x="concept-element-content-model">Content model</span>:</dt>
@@ -52975,7 +52966,6 @@ out of 233&#x2009;257&#x2009;824 bytes available&lt;/meter>&lt;/p></code></pre>
   <dl class="element">
    <dt><span data-x="concept-element-categories">Categories</span>:</dt>
    <dd><span>Flow content</span>.</dd>
-   <dd><span>Sectioning root</span>.</dd>
    <dd><span data-x="category-listed">Listed</span> and <span data-x="category-autocapitalize">autocapitalize-inheriting</span> <span>form-associated element</span>.</dd>
    <dd><span>Palpable content</span>.</dd>
    <dt><span data-x="concept-element-contexts">Contexts in which this element can be used</span>:</dt>
@@ -57719,7 +57709,6 @@ dictionary <dfn dictionary>FormDataEventInit</dfn> : <span>EventInit</span> {
   <dl class="element">
    <dt><span data-x="concept-element-categories">Categories</span>:</dt>
    <dd><span>Flow content</span>.</dd>
-   <dd><span>Sectioning root</span>.</dd>
    <dd><span>Interactive content</span>.</dd>
    <dd><span>Palpable content</span>.</dd>
    <dt><span data-x="concept-element-contexts">Contexts in which this element can be used</span>:</dt>
@@ -58246,7 +58235,6 @@ interface <dfn interface>HTMLDetailsElement</dfn> : <span>HTMLElement</span> {
   <dl class="element">
    <dt><span data-x="concept-element-categories">Categories</span>:</dt>
    <dd><span>Flow content</span>.</dd>
-   <dd><span>Sectioning root</span>.</dd>
    <dt><span data-x="concept-element-contexts">Contexts in which this element can be used</span>:</dt>
    <dd>Where <span>flow content</span> is expected.</dd>
    <dt><span data-x="concept-element-content-model">Content model</span>:</dt>
@@ -121896,7 +121884,6 @@ interface <dfn interface>External</dfn> {
      <th><code>blockquote</code></th>
      <td>A section quoted from another source</td>
      <td><span data-x="Flow content">flow</span>;
-         <span data-x="Sectioning root">sectioning root</span>;
          <span data-x="Palpable content">palpable</span></td>
      <td><span data-x="Flow content">flow</span></td>
      <td><span data-x="Flow content">flow</span></td>
@@ -121908,7 +121895,7 @@ interface <dfn interface>External</dfn> {
     <tr>
      <th><code>body</code></th>
      <td>Document body</td>
-     <td><span data-x="Sectioning root">sectioning root</span></td>
+     <td>none</td>
      <td><code>html</code></td>
      <td><span data-x="Flow content">flow</span></td>
      <td><span data-x="global attributes">globals</span>;
@@ -122095,7 +122082,6 @@ interface <dfn interface>External</dfn> {
      <th><code>details</code></th>
      <td>Disclosure control for hiding details</td>
      <td><span data-x="Flow content">flow</span>;
-         <span data-x="Sectioning root">sectioning root</span>;
          <span data-x="Interactive content">interactive</span>;
          <span data-x="Palpable content">palpable</span></td>
      <td><span data-x="Flow content">flow</span></td>
@@ -122121,8 +122107,7 @@ interface <dfn interface>External</dfn> {
     <tr>
      <th><code>dialog</code></th>
      <td>Dialog box or window</td>
-     <td><span data-x="Flow content">flow</span>;
-         <span data-x="Sectioning root">sectioning root</span></td>
+     <td><span data-x="Flow content">flow</span>;</td>
      <td><span data-x="Flow content">flow</span></td>
      <td><span data-x="Flow content">flow</span></td>
      <td><span data-x="global attributes">globals</span>;
@@ -122202,7 +122187,6 @@ interface <dfn interface>External</dfn> {
      <th><code>fieldset</code></th>
      <td>Group of form controls</td>
      <td><span data-x="Flow content">flow</span>;
-         <span data-x="Sectioning root">sectioning root</span>;
          <span data-x="category-listed">listed</span>;
          <span data-x="Form-associated element">form-associated</span>;
          <span data-x="Palpable content">palpable</span></td>
@@ -122230,7 +122214,6 @@ interface <dfn interface>External</dfn> {
      <th><code>figure</code></th>
      <td>Figure with optional caption</td>
      <td><span data-x="Flow content">flow</span>;
-         <span data-x="Sectioning root">sectioning root</span>;
          <span data-x="Palpable content">palpable</span></td>
      <td><span data-x="Flow content">flow</span></td>
      <td><code>figcaption</code>*;
@@ -122272,7 +122255,7 @@ interface <dfn interface>External</dfn> {
 
     <tr>
      <th><code>h1</code>, <code>h2</code>, <code>h3</code>, <code>h4</code>, <code>h5</code>, <code>h6</code></th>
-     <td>Section heading</td>
+     <td>Heading</td>
      <td><span data-x="Flow content">flow</span>;
          <span data-x="Heading content">heading</span>;
          <span data-x="Palpable content">palpable</span></td>
@@ -122307,9 +122290,8 @@ interface <dfn interface>External</dfn> {
 
     <tr>
      <th><code>hgroup</code></th>
-     <td>heading group</td>
+     <td>Generic Heading container</td>
      <td><span data-x="Flow content">flow</span>;
-         <span data-x="Heading content">heading</span>;
          <span data-x="Palpable content">palpable</span></td>
      <td>
       <code>legend</code>;
@@ -123119,7 +123101,7 @@ interface <dfn interface>External</dfn> {
     <tr>
      <th><code>td</code></th>
      <td>Table cell</td>
-     <td><span data-x="Sectioning root">sectioning root</span></td>
+     <td>none</td>
      <td><code>tr</code></td>
      <td><span data-x="Flow content">flow</span></td>
      <td><span data-x="global attributes">globals</span>;
@@ -123606,19 +123588,6 @@ interface <dfn interface>External</dfn> {
       <code>input</code> (if the <code data-x="attr-input-type">type</code> attribute is <em>not</em> in the <span data-x="attr-input-type-hidden">Hidden</span> state);
       <code>video</code> (if the <code data-x="attr-media-controls">controls</code> attribute is present)
 
-    <tr>
-     <td> <span data-x="sectioning root">Sectioning roots</span>
-     <td>
-      <code>blockquote</code>;
-      <code>body</code>;
-      <code>details</code>;
-      <code>dialog</code>;
-      <code>fieldset</code>;
-      <code>figure</code>;
-      <code>td</code>
-     <td>
-      &mdash;
-
     <tr>
      <td> <span data-x="form-associated element">Form-associated elements</span>
      <td>