Expand/clarify understanding for 1.4.4 Resize Text

Relates to #2169 and questions about whether a site that break using "text-only" resizing fails, even if zooming works

understanding/20/resize-text.html

@@ -15,31 +15,35 @@ <h2>Intent of Resize text</h2>
 
       <p>The intent of this Success Criterion is to ensure that visually rendered text, including
          text-based controls (text characters that have been displayed so that they can be
-         seen [vs. text characters that are still in data form such as ASCII]) can be scaled
+         seen, rather than text characters that are still in data form such as ASCII) can be scaled
          successfully so that it can be read directly by people with mild visual disabilities,
          without requiring the use of assistive technology such as a screen magnifier. Users
          may benefit from scaling all content on the Web page, but text is most critical. 
       </p>
 
       <p>The scaling of content is primarily a user agent responsibility. User agents that
          satisfy 
-         <a href="https://www.w3.org/TR/WAI-USERAGENT/guidelines.html#tech-configure-text-scale">UAAG 1.0 Checkpoint 4.1</a> allow users to configure text scale. The author's responsibility is to create Web
-         content that does not prevent the user agent from scaling the content effectively.
+         <a href="https://www.w3.org/TR/WAI-USERAGENT/guidelines.html#tech-configure-text-scale">UAAG 1.0 Checkpoint 4.1</a>
+         allow users to configure text scale through a number of mechanisms - including zoom (of the entire page's content),
+         magnification, text-only resizing, and allowing the user to configure a reference size for rendered text.
+         The author's responsibility is to create Web content that does not prevent the user agent from scaling the content effectively.
          Authors may satisfy this Success Criterion by verifying that content does not interfere
          with user agent support for resizing text, including text-based controls, or by providing
          direct support for resizing text or changing the layout. An example of direct support
          might be via server-side script that can be used to assign different style sheets.
       </p>
+
+      <p>Content satisfies the Success Criterion if it can be scaled up to 200% using at least one text scaling
+         mechanism supported by user agents.</p>
 
       <p>The author cannot rely on the user agent to satisfy this Success Criterion for HTML
-         content if users do not have access to a user agent with zoom support. For example,
-         if they work in an environment that requires them to use IE 6.
+         through a specific text scaling mechanism if users do not have access to a user agent with that particular mechanism.
       </p>
 
-      <p>If the author is using a technology whose user agents do not provide zoom support,
-         the author is responsible to provide this type of functionality directly or to provide
-         content that works with the type of functionality provided by the user agent. If the
-         user agent doesn't provide zoom functionality but does let the the user change the
+      <p>If the author is using a technology whose user agents do not provide support for specific text scaling mechanisms,
+         the author is responsible for providing this type of functionality directly, or to provide
+         content that works with the type of functionality provided by the user agent. For instance, if the
+         user agent doesn't provide full-page zoom functionality, but does let the the user change the
          text size, the author is responsible for ensuring that the content remains usable
          when the text is resized. 
       </p>
@@ -58,7 +62,7 @@ <h2>Intent of Resize text</h2>
          can be accessed, is provided to the user in some way besides the fact that it is truncated.
       </p>
 
-      <p>Content satisfies the Success Criterion if it can be scaled up to 200%, that is, up
+      <p>Content satisfies the Success Criterion if it can be scaled up to 200% - that is, up
          to twice the width and height. Authors may support scaling beyond that limit, however,
          as scaling becomes more extreme, adaptive layouts may introduce usability problems.
          For example, words may be too wide to fit into the horizontal space available to them,
@@ -73,7 +77,7 @@ <h2>Intent of Resize text</h2>
          a minimum magnification of 200%. Above 200%, zoom (which resizes text, images, and
          layout regions and creates a larger canvas that may require both horizontal and vertical
          scrolling) may be more effective than text resizing. Assistive technology dedicated
-         to zoom support would usually be used in such a situation and may provide better accessibility
+         to zoom support would usually be used in such a situation, and may provide better accessibility
          than attempts by the author to support the user directly.
       </p>
 
@@ -131,7 +135,7 @@ <h2>Examples of Resize text</h2>
          </li>
 
          <li>
-            A user uses a zoom function in his user agent to change the scale of the content.
+            A user uses a full-page zoom function in his user agent to change the scale of the content.
             All the content scales uniformly, and the user agent provides scroll bars, if necessary.
 
          </li>