--- a/ttml-ww-profiles/ttml-ww-profiles.html	Mon Sep 21 11:30:31 2015 -0700
+++ b/ttml-ww-profiles/ttml-ww-profiles.html	Mon Sep 21 13:00:15 2015 -0700
@@ -484,6 +484,8 @@
     <p><dfn data-dfn-type="dfn" id="dfn-related-media-object">Related Media Object</dfn>. See Section 2.2 at [<cite><a class="bibref" href="#bib-TTML1">TTML1</a></cite>].</p>
 		
 		<p><dfn data-dfn-type="dfn" id="dfn-related-video-object">Related Video Object</dfn>. A <a href="#dfn-related-media-object" class="internalDFN" data-link-type="dfn">Related Media Object</a> that consists of a sequence of image frames, each a rectangular array of pixels.</p> 
+		
+		<p><dfn data-dfn-type="dfn" id="dfn-text-alternative">text alternative</dfn>. As defined in [<cite><a class="bibref" href="#bib-WCAG20">WCAG20</a></cite>].</p>
 
   </section>
 
@@ -1997,12 +1999,9 @@
       <p>If a <code>smpte:backgroundImage</code> attribute is applied to a <code>div</code> element:
 
       </p><ul>
-        <li>the width and height of the region extent associated with the <code>div</code> element <em class="rfc2119" title="SHALL">SHALL</em> be specified and <em class="rfc2119" title="SHALL">SHALL</em> be
-        equal to the width and height of the image source referenced by the <code>smpte:backgroundImage</code>;</li>
-
-        <li>the <code>metadata</code> element of the <code>div</code> element <em class="rfc2119" title="SHOULD">SHOULD</em> contain an instance of
-        <code>ittm:altText</code> that is a verbatim text equivalent of the image referenced by the
-        <code>smpte:backgroundImage</code> attribute; and</li>
+        <li>the width and height of the image source referenced by  <code>smpte:backgroundImage</code> <em class="rfc2119" title="SHALL">SHALL</em> be equal to width and height of the extent of the region in which the <code>div</code> element is presented;</li>
+
+        <li>the <code>div</code> element <em class="rfc2119" title="SHOULD">SHOULD</em> contain a <code>metadata</code> element containing an <code>ittm:altText</code> element that is a <a href="#dfn-text-alternative" class="internalDFN" data-link-type="dfn">text alternative</a> of the image referenced by the <code>smpte:backgroundImage</code> attribute; and</li>
 
         <li>The <code>smpte:backgroundImage</code> attribute <em class="rfc2119" title="SHALL">SHALL</em> reference a complete image that conforms to the PNG image coding
         as specified in Sections 7.1.1.3 and 15.1 of [<cite><a class="bibref" href="#bib-MHP">MHP</a></cite>]. If a pHYs chunk is present, it <em class="rfc2119" title="SHALL">SHALL</em> indicate square pixels. Note:

--- a/ttml-ww-profiles/ttml-ww-profiles.source.html	Mon Sep 21 11:30:31 2015 -0700
+++ b/ttml-ww-profiles/ttml-ww-profiles.source.html	Mon Sep 21 13:00:15 2015 -0700
@@ -122,6 +122,8 @@
     <p><dfn>Related Media Object</dfn>. See Section 2.2 at [[!TTML1]].</p>
 		
 		<p><dfn>Related Video Object</dfn>. A <a>Related Media Object</a> that consists of a sequence of image frames, each a rectangular array of pixels.</p> 
+		
+		<p><dfn>text alternative</dfn>. As defined in [[!WCAG20]].</p>
 
   </section>
 
@@ -1642,12 +1644,9 @@
       <p>If a <code>smpte:backgroundImage</code> attribute is applied to a <code>div</code> element:
 
       <ul>
-        <li>the width and height of the region extent associated with the <code>div</code> element SHALL be specified and SHALL be
-        equal to the width and height of the image source referenced by the <code>smpte:backgroundImage</code>;</li>
-
-        <li>the <code>metadata</code> element of the <code>div</code> element SHOULD contain an instance of
-        <code>ittm:altText</code> that is a verbatim text equivalent of the image referenced by the
-        <code>smpte:backgroundImage</code> attribute; and</li>
+        <li>the width and height of the image source referenced by  <code>smpte:backgroundImage</code> SHALL be equal to width and height of the extent of the region in which the <code>div</code> element is presented;</li>
+
+        <li>the <code>div</code> element SHOULD contain a <code>metadata</code> element containing an <code>ittm:altText</code> element that is a <a>text alternative</a> of the image referenced by the <code>smpte:backgroundImage</code> attribute; and</li>
 
         <li>The <code>smpte:backgroundImage</code> attribute SHALL reference a complete image that conforms to the PNG image coding
         as specified in Sections 7.1.1.3 and 15.1 of [[!MHP]]. If a pHYs chunk is present, it SHALL indicate square pixels. Note: