Bidi rewrites to handle <http://www.w3.org/mid/0b6b01cd34267944da0gmail.com> (<http://www.w3.org/mid/CA+FsOYYKGsKOrAoJ55jcYvYHVcWRojX4_KaCBfpQZSn8w=d3Ug@mail.gmail.com>) and hopefully align with future addition of isolation to Unicode bidi.

Author: fantasai

css3-writing-modes/Overview.html

@@ -32,15 +32,15 @@
 
    <h1>CSS Writing Modes Module Level 3</h1>
 
-   <h2 class="no-num no-toc" id=longstatus-date>Editor's Draft 25 June 2012</h2>
+   <h2 class="no-num no-toc" id=longstatus-date>Editor's Draft 26 June 2012</h2>
 
    <dl>
     <dt>This version:
 
     <dd><a
      href="http://dev.w3.org/csswg/css3-writing-modes/">http://dev.w3.org/csswg/css3-writing-modes/</a>
      <!--
-    <dd><a href="http://www.w3.org/TR/2012/WD-css3-writing-modes-20120625/">http://www.w3.org/TR/2012/ED-css3-writing-modes-20120625/</a>
+    <dd><a href="http://www.w3.org/TR/2012/WD-css3-writing-modes-20120626/">http://www.w3.org/TR/2012/ED-css3-writing-modes-20120626/</a>
 -->
 
 
@@ -533,17 +533,21 @@ <h2 id=text-direction><span class=secno>2. </span> Inline Direction and
 
   <p>User agents that support bidirectional text must apply the Unicode
    bidirectional algorithm to every sequence of inline-level boxes
-   uninterrupted by a forced (<a
+   uninterrupted by any block boundary or “<a
    href="http://www.unicode.org/reports/tr9/#Bidirectional_Character_Types">bidi
-   class B</a>) paragraph break or block boundary. This sequence forms the
-   <dfn id=paragraph>paragraph</dfn> unit in the bidirectional algorithm.
+   type B</a>” <dfn id=forced-paragraph-break>forced paragraph break</dfn>.
+   This sequence forms the <dfn id=paragraph
+   title="bidi paragraph">paragraph</dfn> unit in the bidirectional
+   algorithm. Additionally, any such sequence forming part or all of the
+   contents of a <a href="#bidi-isolate"><i>bidi-isolated</i></a> inline
+   element also forms a <a href="#paragraph"><i>bidi paragraph</i></a>.
 
   <p>Two CSS properties, ‘<a href="#direction0"><code
    class=property>direction</code></a>’ and ‘<a
    href="#unicode-bidi0"><code class=property>unicode-bidi</code></a>’,
    provide explicit embedding and override controls in the CSS layer. Because
-   the base direction of a text depends on the structure and semantics of the
-   document, the ‘<a href="#direction0"><code
+   the base directionality of a text depends on the structure and semantics
+   of the document, the ‘<a href="#direction0"><code
    class=property>direction</code></a>’ and ‘<a
    href="#unicode-bidi0"><code class=property>unicode-bidi</code></a>’
    properties should in most cases be used only to map bidi information in
@@ -552,16 +556,19 @@ <h2 id=text-direction><span class=secno>2. </span> Inline Direction and
    those features instead</strong> and not specify CSS rules to override
    them.
 
-  <p>Except when the ‘<a href="#plaintext"><code
-   class=css>plaintext</code></a>’ value of ‘<a
-   href="#unicode-bidi0"><code class=property>unicode-bidi</code></a>’ is
-   in effect, the paragraph embedding level is set according to the value of
-   the ‘<a href="#direction0"><code class=property>direction</code></a>’
-   property of the paragraph's element rather than by the heuristic given in
-   steps P2 and P3 of the Unicode algorithm. The paragraph's element is
-   usually the containing block, but in the case of a paragraph contained by
-   bidi <a href="#isolate">isolation</a> it is the isolating inline element
-   instead.
+  <p>In general, the paragraph embedding level is set according to the ‘<a
+   href="#direction0"><code class=property>direction</code></a>’ property
+   of the element <i>immediately containing</i> the paragraph rather than by
+   the heuristic given in steps P2 and P3 of the Unicode algorithm. <a
+   href="#UAX9" rel=biblioentry>[UAX9]<!--{{!UAX9}}--></a> When the computed
+   ‘<a href="#unicode-bidi0"><code
+   class=property>unicode-bidi</code></a>’ of the element <i>immediately
+   containing</i> the paragraph is ‘<a href="#plaintext"><code
+   class=css>plaintext</code></a>’, however, the Unicode heuristics are
+   used instead. An element <dfn id=bidi-contains>immediately contains</dfn>
+   a bidi paragraph if the element itself, but none of its descendants, both
+   contains the entire bidi paragraph and is a block container or <a
+   href="#bidi-isolate"><i>bidi-isolating</i></a> inline.
 
   <p>The HTML specifications (<a href="#HTML401"
    rel=biblioentry>[HTML401]<!--{{HTML401}}--></a>, section 8.2, and <a
@@ -762,7 +769,7 @@ <h3 id=unicode-bidi><span class=secno>2.2. </span> Embeddings and
       title="Within the element, content is ordered as if...">Inside</abbr>
 
      <th><abbr
-      title="the element's boundaries were strong characters of the element's 'direction'.">embed</abbr>
+      title="the element's boundaries were strong characters of the element's 'direction'.">scoped</abbr>
 
 
      <td>‘<a href="#embed"><code class=css>embed</code></a>’
@@ -813,22 +820,25 @@ <h3 id=unicode-bidi><span class=secno>2.2. </span> Embeddings and
 
    <dt><dfn id=isolate>isolate</dfn>
 
-   <dd>For the purposes of the Unicode bidirectional algorithm, the contents
-    of the element are considered to be inside a separate, independent
-    paragraph with a base directionality given by the element's ‘<a
-    href="#direction0"><code class=property>direction</code></a>’ property,
-    and for the purpose of bidi resolution in its containing bidi paragraph
-    (if any), the element itself is treated as if it were an Object
+   <dd>On an inline element, <dfn id=bidi-isolate
+    title="bidi-isolate|bidi isolation|isolation">bidi-isolates</dfn> its
+    contents: for the purpose of bidi resolution in its containing bidi
+    paragraph (if any), the element is treated as if it were an Object
     Replacement Character (U+FFFC). (If the element is broken across multiple
     lines, then each box of the element is treated as an Object Replacement
-    Character.)
+    Character.) Within the element, its contents are considered, for the
+    purposes of bidi resolution, to be inside a separate, independent
+    document whose <a href="#paragraph"><i>bidi paragraphs</i></a> are
+    assigned the base directionality given by the element's ‘<a
+    href="#direction0"><code class=property>direction</code></a>’ property.
 
    <dt><dfn id=bidi-override>bidi-override</dfn>
 
-   <dd>For inline elements this creates an override. For block-container
-    elements this creates an override for inline-level descendants not within
-    another block container element. This means that inside the element,
-    reordering is strictly in sequence according to the ‘<a
+   <dd>For inline elements this creates an <dfn id=override>override</dfn>.
+    (For block-container elements this creates an <a
+    href="#override"><i>override</i></a> for inline-level descendants not
+    within another block container element.) This means that inside the
+    element, reordering is strictly in sequence according to the ‘<a
     href="#direction0"><code class=property>direction</code></a>’ property;
     the implicit part of the bidirectional algorithm is ignored. This
     corresponds to adding a LRO (U+202D), for ‘<code class=css>direction:
@@ -838,8 +848,9 @@ <h3 id=unicode-bidi><span class=secno>2.2. </span> Embeddings and
 
    <dt><dfn id=isolate-override>isolate-override<dfn></dfn></dfn>
 
-   <dd>This combines the isolation behavior of ‘<a href="#isolate"><code
-    class=css>isolate</code></a>’ with the override behavior of ‘<a
+   <dd>This combines the <a href="#bidi-isolate"><i>isolation</i></a>
+    behavior of ‘<a href="#isolate"><code class=css>isolate</code></a>’
+    with the <a href="#override"><i>override</i></a> behavior of ‘<a
     href="#bidi-override"><code class=css>bidi-override</code></a>’: to
     surrounding content, it is equivalent to ‘<a href="#isolate"><code
     class=css>isolate</code></a>’, but within the element content is
@@ -851,14 +862,12 @@ <h3 id=unicode-bidi><span class=secno>2.2. </span> Embeddings and
    <dd>
     <p>This value behaves as ‘<a href="#isolate"><code
      class=css>isolate</code></a>’ except that for the purposes of the
-     Unicode bidirectional algorithm, the base directionality of each bidi
-     paragraph immediately contained by the element is determined not by the
-     element's computed ‘<a href="#direction0"><code
-     class=property>direction</code></a>’ as usual, but by following the
-     heuristic in rules P2 and P3 of the Unicode bidirectional algorithm. An
-     element immediately contains a bidi paragraph if the element itself, but
-     none of its descendants, both contains the entire bidi paragraph and is
-     a block container or bidi-isolating inline.
+     Unicode bidirectional algorithm, the base directionality of each of the
+     element's <a href="#paragraph"><i>bidi paragraphs</i></a> is determined
+     by following the heuristic in rules P2 and P3 of the Unicode
+     bidirectional algorithm (rather than by using the ‘<a
+     href="#direction0"><code class=property>direction</code></a>’ property
+     of the element).
   </dl>
 
   <p class=note>Because the ‘<a href="#unicode-bidi0"><code
@@ -877,41 +886,43 @@ <h3 id=unicode-bidi><span class=secno>2.2. </span> Embeddings and
    href="#direction0"><code class=property>direction</code></a>’-dependent
    layout calculations.
 
-  <p>The final order of characters within in each bidi paragraph is the same
-   as if the bidi control codes had been added as described above, markup had
-   been stripped, and the resulting character sequence had been passed to an
-   implementation of the Unicode bidirectional algorithm for plain text that
-   produced the same line-breaks as the styled text.
+  <p>The final order of characters within in each <a
+   href="#paragraph"><i>bidi paragraph</i></a> is the same as if the bidi
+   control codes had been added as described above, markup had been stripped,
+   and the resulting character sequence had been passed to an implementation
+   of the Unicode bidirectional algorithm for plain text that produced the
+   same line-breaks as the styled text.
 
   <p>In this process, replaced elements with ‘<code class=css>display:
    inline</code>’ are treated as neutral characters, unless their ‘<a
    href="#unicode-bidi0"><code class=property>unicode-bidi</code></a>’
-   property has a value other than ‘<a href="#normal"><code
-   class=property>normal</code></a>’, in which case they are treated as
-   strong characters in the ‘<a href="#direction0"><code
+   property is either ‘<a href="#embed"><code
+   class=property>embed</code></a>’ or ‘<a href="#bidi-override"><code
+   class=property>bidi-override</code></a>’, in which case they are treated
+   as strong characters in the ‘<a href="#direction0"><code
    class=property>direction</code></a>’ specified for the element. All
    other atomic inline-level boxes are treated as neutral characters always.
 
-  <p>If an inline element is broken around a bidi paragraph boundary (e.g. if
-   split by a block or forced paragraph break), then the bidi control codes
-   corresponding to the end of the element are added before the interruption
-   and the codes corresponding to the start of the element are added after
-   it. (In other words, any embedding levels or overrides started by the
-   element are closed at the paragraph break and reopened on the other side
-   of it.)
-
-  <p>Because the Unicode algorithm has a limit of <em
-   title="According to unicode 3.0, chapter 3, section 12, definition BD2.      Specifically, page 58 here: http://www.unicode.org/unicode/uni2book/ch03.pdf">
-   61 levels</em> of embedding, care should be taken not to use <a
-   class=propinst-unicode-bidi href="#unicode-bidi0">‘<code
-   class=property>unicode-bidi</code>’</a> with a value other than ‘<a
+  <p>If an inline element is broken around a <a href="#paragraph"><i>bidi
+   paragraph</i></a> boundary (e.g. if split by a block or <a
+   href="#forced-paragraph-break"><i>forced paragraph break</i></a>), then
+   the bidi control codes corresponding to the end of the element are added
+   before the interruption and the codes corresponding to the start of the
+   element are added after it. (In other words, any embedding levels or
+   overrides started by the element are closed at the paragraph break and
+   reopened on the other side of it.)
+
+  <p>Because the Unicode algorithm has a limit of 61 levels of embedding,
+   care should be taken not to use ‘<a href="#unicode-bidi0"><code
+   class=property>unicode-bidi</code></a>’ with a value other than ‘<a
    href="#normal"><code class=property>normal</code></a>’ unless
    appropriate. In particular, a value of ‘<code
-   class=property>inherit</code>’ should be used with extreme caution.
-   However, for elements that are, in general, intended to be displayed as
-   blocks, a setting of ‘<code class=css>unicode-bidi: isolate</code>’ is
-   preferred to keep the element together in case display is changed to
-   inline (see example below).
+   class=css>inherit</code>’ should be used with extreme caution. However,
+   for elements that are, in general, intended to be displayed as blocks, a
+   setting of ‘<code class=css>unicode-bidi: isolate</code>’ is preferred
+   to keep the element together in case the ‘<code
+   class=property>display</code>’ is changed to ‘<code
+   class=css>inline</code>’ (see example below).
 
   <h3 id=bidi-example><span class=secno>2.3. </span> Example of Bidirectional
    Text</h3>
@@ -4272,6 +4283,15 @@ <h3 class=no-num id=normative-references> Normative references</h3>
     </dd>
    <!---->
 
+   <dt id=UAX9>[UAX9]
+
+   <dd>Mark Davis. <a
+    href="http://www.unicode.org/reports/tr9/"><cite>Unicode Bidirectional
+    Algorithm.</cite></a> 16 January 2012. Unicode Standard Annex #9. URL: <a
+    href="http://www.unicode.org/reports/tr9/">http://www.unicode.org/reports/tr9/</a>
+    </dd>
+   <!---->
+
    <dt id=UNICODE>[UNICODE]
 
    <dd>The Unicode Consortium. <a