[css-text] text-justify:auto re-worked as per the resolution at Seoul F2F <http://lists.w3.org/Archives/Public/www-style/2014Jun/0167.html>

Author: kojiishi

css-text/Overview.bs

@@ -1558,17 +1558,6 @@ Canonical order: N/A
         <dd>The UA determines the justification algorithm to follow, based
           on a balance between performance and adequate presentation quality.
           UAs should, where possible, use a justification algorithm appropriate to the text.
-          <p class="example">
-          For example, the UA could use by default a justification method that is a
-          simple universal compromise for all writing systems&mdash;such as
-          primarily expanding <i>word separators</i>
-          along with secondarily expanding between CJK and Southeast Asian <i>visually-perceived letters</i>.
-          Then, in cases where the <i>content language</i> of the paragraph is known,
-          it could choose a more language-tailored justification behavior
-          e.g. following [[JLREQ]] for Japanese,
-          using cursive elongation for Arabic,
-          using ''inter-word'' for German,
-          etc.
 
         <div class="figure" id="fig-text-justify-cursive">
           <p>
@@ -1657,6 +1646,13 @@ Expanding and Compressing Text</h4>
     (such as font size, letter-spacing, glyph shape, position within the line, etc.)
     may influence the distribution of space to <i>justification opportunities</i> within the line.
 
+  <p>The UA may enable or break optional ligatures or use other font features
+  such as alternate glyphs or glyph compression
+  to help justify the text under any method.
+  This behavior is not controlled by this level of CSS.
+  However, UAs <em>must not</em> break required ligatures
+  or otherwise disable features required to correctly shape complex scripts.
+
 <h4 id="justify-symbols">
 Handling Symbols and Punctuation</h4>
 
@@ -1706,6 +1702,32 @@ Cursive Scripts</h4>
 <h4 id="justify-algos">
 Possible Algorithms</h4>
 
+  <p>For <a value for=text-justify>auto</a> justification, this specification does not define
+	what all of the <i>justification opportunities</i> are,
+	how they are prioritized, or
+	when and how multiple levels of <i>justification opportunities</i> interact.
+	However, it does require that if a <i>justification opportunity</i> exists within a line,
+	it must be justified,
+	and that, unless contraindicated by the typographic traditions of the content language or adjacent symbols/punctuation,
+	each of the following provides a <i>justification opportunity</i>:
+	<ul>
+	<li><i>Word separators</i>
+	<li>The boundary between a <i>visually-perceived character</i> of any <i>block scripts</i> and any other <i>visually-perceived character</i>
+	<li>The boundary between a <i>visually-perceived character</i> of any <i>clustered scripts</i> and any other <i>visually-perceived character</i>
+	</ul>
+
+  <p class="example">
+	For example, the UA could use by default a justification method that is a
+	simple universal compromise for all writing systems&mdash;such as
+	primarily expanding <i>word separators</i>
+	along with secondarily expanding between CJK and Southeast Asian <i>visually-perceived letters</i>.
+	Then, in cases where the <i>content language</i> of the paragraph is known,
+	it could choose a more language-tailored justification behavior
+	e.g. following [[JLREQ]] for Japanese,
+	using cursive elongation for Arabic,
+	using ''inter-word'' for German,
+	etc.
+
   <p>The guidelines in this level of CSS do not describe a complete
   justification algorithm. They are merely a minimum set of requirements
   that a complete algorithm should meet. Limiting the set of requirements
@@ -1747,13 +1769,6 @@ Possible Algorithms</h4>
     Or it could keep the rule, but only enable it when the content language is known to be Japanese.
   </div>
 
-  <p>The UA may enable or break optional ligatures or use other font features
-  such as alternate glyphs or glyph compression
-  to help justify the text under any method.
-  This behavior is not controlled by this level of CSS.
-  However, UAs <em>must not</em> break required ligatures
-  or otherwise disable features required to correctly shape complex scripts.
-
 <h2 id="spacing">
   Spacing</h2>
 
@@ -2445,18 +2460,34 @@ Appendix B: Default UA Stylesheet</h2>
     with <kbd>[css-text]</kbd> in the subject line.</p>
 
 <h2 class="no-num" id="script-groups">
-Appendix C: Cursive Scripts</h2>
+Appendix C: Scripts and Spacing</h2>
 
   <p><em>This appendix is normative.</em></p>
-  
-  <p>The following scripts in Unicode 6 are considered to be <dfn title="cursive script">cursive scripts</dfn>,
+
+  <p>Typographic behavior varies somewhat by language, but varies drastically by writing system.
+  	This appendix categorizes some common scripts in Unicode 6.0 according to their justification and spacing behavior.
+  	Category descriptions are descriptive, not prescriptive;
+  	the determining factor is the prioritization of <i>justification opportunities</i>.
+
+  <dl>
+  	<dt><dfn>block scripts</dfn></dt>
+  	<dd>CJK and by extension all Wide characters. (See [[!UAX11]])
+  	  The following scripts are included: Bopomofo, Han, Hangul, Hiragana, Katakana, Yi
+  	<dt><dfn>clustered scripts</dfn></dt>
+  	<dd>Scripts that have discrete units but do not use spaces between words, such as many Southeast Asian systems.
+  	  The following scripts are included: Javanese, Khmer, Lao, Myanmar, Thai,
+  	  <span class=issue>This list is likely incomplete. What else fits here?</span>
+  	<dt><dfn title="cursive script">cursive scripts</dfn>
+  	<dd>
+  <p>The following scripts in Unicode 6 are considered to be cursive scripts,
     and do not admit gaps between their letters for either justification or 'letter-spacing':
       Arabic,
       Mandaic,
       Mongolian,
       N'Ko,
       Phags Pa,
       Syriac
+  </dl>
   <p>User agents should update this list as they update their Unicode support
     to handle as-yet-unencoded cursive scripts in future versions of Unicode,
     and are encouraged to ask the CSSWG to update this spec accordingly.