[css-text-3] Add example for segment break transformation. w3c#3461

Author: fantasai

css-text-3/Overview.bs

@@ -1301,7 +1301,49 @@ Characters and Letters</h3>
         removed any tabs and spaces after the segment break before these checks
         take place.</p>
 
-      <p class="feedback issue">Comments on how well this would work in practice would
+      <div class="example">
+        The purpose of the segment break transformation rules
+        (and white space collapsing in general)
+        is to “unbreak” text that has been
+        <a href="#white-space-processing">broken into segments</a>
+        to make the document source code easier to work with.
+        In languages that use word separators, such as English and Korean,
+        “unbreaking” a line requires joining the two lines with a space.
+
+        <figure>
+          <pre>
+            Here is an English paragraph
+            that is broken into multiple lines
+            in the source code so that it can
+            more easily read in a text editor.
+          </pre>
+          <p>Here is an English paragraph that is broken into multiple lines in the source code so that it can be more easily read in a text editor.</p>
+          <figcaption>
+            Eliminating a line break in English requires maintaining a space in its place.
+          </figcaption>
+        </figure>
+
+        In languages that have no word separators, such as Chinese,
+        “unbreaking” a line requires joining the two lines with no intervening space.
+
+        <figure>
+          <pre>
+            这个段落是呢么长，
+            在一行写不行。最好
+            用三行写。
+          </pre>
+          <p>这个段落是呢么长，在一行不行。最好用三行写。</p>
+          <figcaption>
+            Eliminating a line break in Chinese requires eliminating any intervening white space.
+          </figcaption>
+        </figure>
+
+        The segment break transformation rules thus use adjacent context
+        to either transform the segment break into a space
+        or eliminate it entirely.
+      </div>
+
+      <p class="feedback issue">Comments on how well these rules would work in practice would
         be very much appreciated, particularly from people who work with
         Thai and similar scripts.
         Note that browser implementations do not currently follow these rules consistently