Clean up prose relating to vertical typesetting.

Author: fantasai

css3-writing-modes/Overview.src.html

@@ -1127,14 +1127,10 @@ <h3 id="text-orientation">
     and sets the orientation of the line. Current values only
     have an effect in vertical writing modes.
 
-  <p id=grapheme-cluster>In this section only, the term <dfn>character</dfn>
-   is defined as <em>extended grapheme cluster</em> per [[!UAX29]]. It is
-   roughly equivalent to what a language user considers to be a character
-   or a basic unit of the script (which might not be a single Unicode
-   codepoint).
-   The UA may further tailor the definition as allowed by Unicode.
-   See <a href="#character-properties">Character Properties</a> for detailed
-   information on determing character properties.
+  <p>For readability, the term <i>character</i> is used in place of
+    <em>extended grapheme cluster</em> in this section.
+    See <a href="#character-properties">Characters and Properties</a>
+    for further details.
 
   <p>Values have the following meanings:</p>
 
@@ -1217,6 +1213,21 @@ <h3 id="text-orientation">
       (writing-mode is vertical-rl)</p>
   </div>
 
+  <p>The orientation of characters belonging to the Common, Inherited, and Unknown
+    script categories may be UA- or font-dependent in vertical typographic
+    modes:
+  <ul>
+    <li><p>If the font and font system support mixed-orientation typesetting
+      (e.g. the OpenType font used has the <code>vrt2</code>), the
+      UA should rely on that feature to set ''vertical-right'' text. Similarly
+      if the font and font system support upright typesetting
+      (e.g. the OpenType font used has the <code>vert</code> feature) then the
+      UA should rely on that feature to set ''upright'' text.
+    <li><p>If the UA needs to synthesize such features,
+      then the settings in <a href="#vertical-typesetting-details">Appendix C</a>
+      are recommended.
+  </ul>
+
   <div class="example">
     <p>In the following example, the root element of a horizontal-only document
       is set to use ''sideways''. In the rest of the document, the author
@@ -1230,32 +1241,6 @@ <h3 id="text-orientation">
     </pre>
   </div>
 
-<h4 id="vertical-typesetting">
-Vertical Typesetting</h4>
-
-  <p>In vertical typographic modes, any character belonging to a
-    vertical script <em>must</em> be set using its base character's
-    intrinsic orientation. (See <a href="#script-orientations">Appendix B</a>.)
-    Characters belonging to horizontal-only scripts must set sideways
-    (for ''vertical-right'') or set upright (for ''upright'') depending on the
-    'text-orientation' property.
-    
-  <p>The orientation of characters belonging to the Common, Inherited, and Unknown
-    script categories may be UA- or font-dependent in vertical typographic
-    modes:
-
-  <ul>
-    <li><p>If the font and font system support mixed-orientation typesetting, the
-      UA should rely on that feature to set ''vertical-right'' text. Similarly
-      if the font and font system support upright typesetting then the UA should
-      rely on that feature to set ''upright'' text.
-    
-    <li><p>If the UA needs to synthesize such features (e.g. if an OpenType font
-      has only the <code>vert</code> but not the <code>vrt2</code> feature),
-      then the settings in <a href="#vertical-typesetting-details">Appendix C</a>
-      are recommended.
-  </ul>
-
 <h2 id="abstract-box">
 Abstract Box Terminology</h2>
 
@@ -2228,6 +2213,38 @@ <h2 id="bidi-html" class=no-num>
 { unicode-bidi: isolate; }
   </pre>
 
+<h2 id="character-properties" class="no-num">Appendix Q
+Characters and Properties</h2>
+
+  <p>Unicode defines three character-level properties that are referenced
+    in CSS Writing Modes:
+  <dl>
+    <dt><a href="http://www.unicode.org/reports/tr11/#Definitions">East Asian width</a>
+    <dd>Defined in [[!UAX11]] and given as the East_Asian_Width property.
+    <dt><a href="http://www.unicode.org/reports/tr44/#General_Category_Values">General Category</a>
+    <dd>Defined in [[!UAX44]] and given as the General_Category property.
+    <dt><a href="http://www.unicode.org/reports/tr24/#Values">Script property</a>
+    <dd>Defined in [[!UAX24]] and given as the Script property. (UAs should
+      include any ScriptExtensions.txt assignments in this mapping.)
+  </dl>
+
+  <p id=grapheme-cluster>In several sections (as noted), the term
+    <dfn>character</dfn> is defined as <em>extended grapheme cluster</em>
+    per [[!UAX29]]. It is roughly equivalent to what a language user
+    considers to be a character or a basic unit of the script (which
+    might not be a single Unicode codepoint).
+    The UA may further tailor this definition as allowed by Unicode.
+
+  <p>Unicode defines properties for characters, but for 'text-orientation' and
+    <a href="vertical-typesetting-details">Vertical Typesetting Synthesis</a>,
+    it is necessary to determine the properties of a grapheme cluster.
+    For the purposes of CSS Writing Modes, the properties of a grapheme
+    cluster are given by its base character&#8212;except in one case:
+    grapheme clusters formed with an Enclosing Mark (Me) of the Common
+    script are considered to be Other Symbols (So) in the Common script.
+    They are assumed to have the same Unicode properties as the
+    Replacement Character U+FFFD.
+
 <h2 class="no-num" id="script-orientations">Appendix B:
 Bi-orientational Transformations</h2>
   <p><em>This section is normative.</em></p>
@@ -2277,6 +2294,14 @@ <h2 id="vertical-typesetting-details" class="no-num">Appendix C:
 
   <p><em>This appendix is non-normative.</em></p>
 
+  <p>This section defines an algorithm for automatic typesetting of
+    vertical text.
+
+    For readability, the term <i>character</i> is used in place of
+    <em>extended grapheme cluster</em> in this section.
+    See <a href="#character-properties">Characters and Properties</a>
+    for further details.
+
   <p class="issue">This section needs careful review.</p>
 
   <p>When 'text-orientation' is either ''vertical-right'' or ''upright'',
@@ -2296,7 +2321,7 @@ <h2 id="vertical-typesetting-details" class="no-num">Appendix C:
       font settings if possible).
     <li>Set any other characters that are assigned to a script
       (i.e. do not belong to the Common, Inherited, or Unknown scripts)
-      <a href="#vertical-typesetting">as required by 'text-orientation'</a>.
+      as required by 'text-orientation' and <a href="#script-orientations">Appendix B</a>.
   </ol>
 
   <p>When 'text-orientation' is ''vertical-right'', the following settings
@@ -2352,30 +2377,6 @@ <h2 id="vertical-typesetting-details" class="no-num">Appendix C:
     If any of these are present, the font is considered to have vertical
     font settings available.
 
-<h2 id="character-properties" class="no-num">Appendix Q
-Characters and Properties</h2>
-
-  <p>Unicode only defines properties for characters, but in the definition
-    of 'text-orientation' and in
-    <a href="vertical-typesetting-details">Vertical Typesetting Synthesis</a>,
-    it is necessary to determine the properties of a grapheme cluster.
-    For the purposes of CSS Writing Modes, the properties of a grapheme
-    cluster are given by its base character&#8212;except in one case:
-    grapheme clusters formed with an Enclosing Mark (Me) of the Common
-    script are considered to be Other Symbols (So) in the Common script
-    having the same Unicode properties as the Replacement Character U+FFFD.
-
-  <p>Unicode defines three properties that are referenced here:
-  <dl>
-    <dt><a href="http://www.unicode.org/reports/tr11/#Definitions">East Asian width</a>
-    <dd>Defined in [[UAX11]] and given as the East_Asian_Width property.
-    <dt><a href="http://www.unicode.org/reports/tr44/#General_Category_Values">General Category</a>
-    <dd>Defined in [[UAX44]] and given as the General_Category property.
-    <dt><a href="http://www.unicode.org/reports/tr24/#Values">Script property</a>
-    <dd>Defined in [[UAX24]] and given as the Script property. (UAs should
-      include any ScriptExtensions.txt assignments in this mapping.)
-  </dl>
-
 <h2 id="intrinsic-sizing" class="no-num">Appendix D:
 Intrinsic Dimensions</h2>