initial draft for #1216

Author: cookiecrook

index.html

@@ -1479,6 +1479,7 @@ <h3>Landmark Roles</h3>
         <section id="live_region_roles">
           <h3>Live Region Roles</h3>
           <p>The following <a>roles</a> are <a>live regions</a> and can be modified by <a href="#attrs_liveregions">live region attributes</a>.</p>
+          <p>Typically, assistive technology only speaks <em>changes</em> to a live region, not the initial contents of a live region. To ensure content in a live region is announced, authors SHOULD create an rendered but empty live region as early as possible (such as on page load), and then add content to the live region when the author wishes it to be announced. The exception to this live region convention is <code>alert</code>, due to system accessiblity notifications events required for the role. While an <rref>alert</rref> is a live region, its content is announced by assistive technology when the alert is rendered on the page and when the content changes.</p>
           <ul>
             <li><rref>alert</rref></li>
             <li><rref>log</rref></li>
@@ -1506,13 +1507,10 @@ <h2>Definition of Roles</h2>
           <div class="role-description">
             <p>A type of <a>live region</a> with important, and usually time-sensitive, information. See related <rref>alertdialog</rref> and <rref>status</rref>.</p>
             <p>
-              Alerts are used to convey messages that might be immediately important to users. In the case of audio warnings, alerts provide an accessible alternative for hearing-impaired users. The
-              <code>alert</code> <a>role</a> is applied to the element containing the alert message. An <code>alert</code> is a specialized form of the <rref>status</rref> role, which is processed as
-              an atomic <a>live region</a>.
+              Alerts are used to convey messages that will be immediately important to users. In the case of audio warnings, alerts provide an accessible alternative for Deaf or hard-of-hearing users. The <code>alert</code> <a>role</a> is applied to the element containing the alert message.
             </p>
             <p>
-              Alerts are assertive live regions, which means they cause immediate notification for assistive technology users. If the operating system allows, the <a>user agent</a> SHOULD fire a
-              system alert <a>event</a> through the accessibility API when the <abbr title="Accessible Rich Internet Applications">WAI-ARIA</abbr> alert is created.
+              Alert is a special type of assertive live region that is intended to cause immediate notification for assistive technology users. If the operating system allows, the <a>user agent</a> SHOULD fire a system alert <a>event</a> through the accessibility API when the alert is rendered.
             </p>
             <p>
               Neither authors nor user agents are required to set or manage focus to an alert in order for it to be processed. Since alerts are not required to receive focus, authors SHOULD NOT
@@ -1612,6 +1610,9 @@ <h2>Definition of Roles</h2>
               dialog. Authors SHOULD make alert dialogs modal by ensuring that, while the <code>alertdialog</code> is shown, keyboard and mouse interactions only operate within the dialog. See
               <pref>aria-modal</pref>.
             </p>
+            <p>
+              Alertdialog is a special type of dialog that is intended to cause an immediate, alert-level notification for assistive technology users. If the operating system allows, the <a>user agent</a> SHOULD fire a system alert <a>event</a> through the accessibility API when the alerdialog is rendered.
+            </p>
             <p>
               Unlike <rref>alert</rref>, <code>alertdialog</code> can receive a response from the user. For example, to confirm that the user understands the alert being generated. When the alert
               dialog is displayed, authors SHOULD set focus to an active element within the alert dialog, such as a form control or confirmation button. The <a>user agent</a> SHOULD fire a system