"Notes" preface to HTML-AAM role mappings

Proposing using the “Notes” preface to the role mapping table to
address issues #177, #159, and possibly #172.

html-aam/html-aam.html

@@ -166,8 +166,22 @@ <h3>HTML Element Role Mappings</h3>
  <li>HTML elements with default WAI-ARIA role semantics <span class="rfc2119">must</span> be mapped to platform <a class="termref" data-lt="accessibility API">accessibility APIs</a> according to those WAI-ARIA roles' mappings as defined in the <a href="http://www.w3.org/TR/core-aam-1.1/">Core Accessibility API Mappings</a> [[!CORE-AAM]] specification.</li>
  <li>A '?' in a cell indicates the data has yet to be provided.</li>
  <li>"Not mapped" (Not Applicable) means the element does not need to be exposed via an <a class="termref">accessibility API</a>. This is usually because the element is not displayed as part of the user interface.</li>
- <li>User agents should return a user-presentable, localized string value for the Mac Accessibility AXRoleDescription.</li>
- <li>All elements having an accessible object in IAccessible2 mapping are supposed to implement IAccessible, IAccessible2 and IAccessible2_2 interfaces.</li>
+ <li><strong>IAccessible2:</strong>
+ <ul>
+ <li>All elements with accessible objects should implement the IAccessible, IAccessible2 and IAccessible2_2 interfaces.</li>
+ </ul>
+ </li>
+ <li><strong>UIA:</strong>
+ <ul>
+ <li>When a <a href="https://www.w3.org/TR/html51/sec-forms.html#labelable-element">labelable element</a> is referenced by a <code>label</code> element's <code>for</code> attribute, or a descendant of a <code>label</code> element, the labelable element's UIA <code>LabeledBy</code> property points to the UIA element for the <code>label</code> element.</li>
+ <li>Elements mapped to the <code>Text</code> Control Type are not generally represented as <a class="termref" data-lt="accessible object">accessible objects</a> in the <a class="termref">accessibility tree</a>, but are just part of the <code>Text</code> Control Pattern implemented for the whole HTML document. However, if they have any <code>aria-</code> attributes or an explict <code>tabindex</code> specified, elements mapped to the <code>Text</code> Control Type will be represented as <a class="termref" data-lt="accessible object">accessible objects</a> in the <a class="termref">accessibility tree</a>.</li>
+ </ul>
+ </li>
+ <li><strong>AXAPI:</strong>
+ <ul>
+ <li>User agents should return a user-presentable, localized string value for the Mac Accessibility AXRoleDescription.</li>
+ </ul>
+ </li>
  </ul>
  <div class="table-container">
  <table class="map-table elements" id="element-mapping-table">