[css-writing-modes] Tr rule was misplaced. Fix that and tweak the wording to make the expectations on fonts clearer.

Author: fantasai

css-writing-modes/Overview.html

@@ -1226,24 +1226,18 @@ <h4 class="heading settled heading" data-level=5.1.1 id=vertical-orientations><s
   <p>
     <a data-biblio-type=normative data-link-type=biblio href=#utr50 title=utr50>[UTR50]</a> defines the Vertical_Orientation property for the default character orientation of mixed-orientation vertical text.
     When <a class=property data-link-type=propdesc href=#propdef-text-orientation title=text-orientation>text-orientation</a> is <a class=css data-link-type=maybe href=#valuedef-mixed title=mixed>mixed</a>,
-    the UA must render a <a data-link-type=dfn href=#character title=character>character</a> upright if its orientation property is
-    <code>U</code> or <code>Tu</code>;
+    the UA must <a href="#typeset-upright">typeset a <a data-link-type=dfn href=#character title=character>character</a> upright</a>
+    if its orientation property is <code>U</code>, <code>Tu</code>, or <code>Tr</code>;
     or <a href=#typeset-sideways>typeset it sideways</a> (90° clockwise from horizontal)
     if its orientation property is <code>R</code>.
-    For <code>Tr</code> <a data-link-type=dfn href=#character title=characters>characters</a>,
-    which are intended to be either transformed or rotated sideways,
-    the UA may assume that appropriate glyphs for upright typesetting
-    are given in the font and render them upright;
-    alternately it may check for such glyphs first,
-    and fall back to typesetting them sideways if the appropriate glyphs are missing.
 
 <h4 class="heading settled heading" data-level=5.1.2 id=vertical-font-features><span class=secno>5.1.2 </span><span class=content>
 Vertical Typesetting and Font Features</span><a class=self-link href=#vertical-font-features></a></h4>
 
   <p>When typesetting text in <a class=css data-link-type=maybe href=#valuedef-mixed title=mixed>mixed</a> and <a class=css data-link-type=maybe href=#valuedef-upright title=upright>upright</a> orientations:
 
   <dl>
-    <dt>upright characters
+    <dt id="typeset-upright">upright characters
     <dd>
       Are typeset upright with vertical font metrics.
       The UA must synthesize vertical font metrics for fonts that lack them.
@@ -1256,7 +1250,6 @@ <h4 class="heading settled heading" data-level=5.1.2 id=vertical-font-features><
       <p class=note>Note that even when typeset "upright",
         some glyphs should appear rotated.
         For example, dashes and enclosing punctuation 
-        (such as 〈 LEFT ANGLE BRACKET U+3008)
         should be oriented relative to the inline axis.
         In OpenType, this is typically handled by glyph substitution,
         although not all fonts have alternate glyphs for all relevant codepoints.
@@ -1265,6 +1258,16 @@ <h4 class="heading settled heading" data-level=5.1.2 id=vertical-font-features><
         Unicode published draft data on which <a data-link-type=dfn href=#character title=characters>characters</a> should appear sideways
         as the SVO property in <a href=http://www.unicode.org/reports/tr50/tr50-6.Orientation.txt>this data file</a>;
         however, this property has been abandoned for the current revision of <a data-biblio-type=normative data-link-type=biblio href=#utr50 title=utr50>[UTR50]</a>.
+
+      <p><a data-link-type=dfn href=#character title=characters>Characters</a>,
+      which are classified as <code>Tr</code> or <code>Tu</code> in <a data-biblio-type=normative data-link-type=biblio href=#utr50 title=utr50>[UTR50]</a>
+      are expected to have alternate glyphs or positioning for typesetting upright in vertical text.
+      In the case of <code>Tr</code> <a data-link-type=dfn href=#character title=characters>characters</a>,
+      if such vertical alternate glyphs are missing from the font,
+      the UA may (but is not required to)
+      fall back to <a href="#typeset-sideways">typesetting them sideways</a>
+      in order to synthesize the missing glyphs.
+
     <dt id=typeset-sideways><a class=self-link href=#typeset-sideways></a>sideways characters 
     <dd>
       Are typeset rotated 90° sideways with horizontal metrics,
@@ -2853,4 +2856,4 @@ <h2 class="no-num heading settled" id=issues-index><span class=content>Issues In
 
 <a href=#issue-afa4af44> ↵ </a><p class=issue>The WG would appreciate a better (more obvious + easier to type) name for this, if anyone can come up with one.
 
-  <a href=#issue-394a8f4a> ↵ </a></div>
+  <a href=#issue-394a8f4a> ↵ </a></div>

css-writing-modes/Overview.src.html

@@ -1211,24 +1211,18 @@ <h4 id='vertical-orientations'>
   <p>
     [[!UTR50]] defines the Vertical_Orientation property for the default character orientation of mixed-orientation vertical text.
     When 'text-orientation' is ''mixed'',
-    the UA must render a <i>character</i> upright if its orientation property is
-    <code>U</code> or <code>Tu</code>;
+    the UA must <a href="#typeset-upright">typeset a <i>character</i> upright</a>
+    if its orientation property is <code>U</code>, <code>Tu</code>, or <code>Tr</code>;
     or <a href="#typeset-sideways">typeset it sideways</a> (90&deg; clockwise from horizontal)
     if its orientation property is <code>R</code>.
-    For <code>Tr</code> <i>characters</i>,
-    which are intended to be either transformed or rotated sideways,
-    the UA may assume that appropriate glyphs for upright typesetting
-    are given in the font and render them upright;
-    alternately it may check for such glyphs first,
-    and fall back to typesetting them sideways if the appropriate glyphs are missing.
 
 <h4 id='vertical-font-features'>
 Vertical Typesetting and Font Features</h4>
 
   <p>When typesetting text in ''mixed'' and ''upright'' orientations:
 
   <dl>
-    <dt>upright characters
+    <dt id='typeset-upright'>upright characters
     <dd>
       Are typeset upright with vertical font metrics.
       The UA must synthesize vertical font metrics for fonts that lack them.
@@ -1238,18 +1232,28 @@ <h4 id='vertical-font-features'>
       (E.g. the OpenType ''vert'' feature must be enabled.)
       Furthermore, characters from horizontal cursive scripts (such as Arabic)
       are shaped in their isolated forms when typeset upright.
+
       <p class="note">Note that even when typeset "upright",
         some glyphs should appear rotated.
         For example, dashes and enclosing punctuation 
-        (such as 〈 LEFT ANGLE BRACKET U+3008)
         should be oriented relative to the inline axis.
         In OpenType, this is typically handled by glyph substitution,
         although not all fonts have alternate glyphs for all relevant codepoints.
         (East Asian fonts usually provide alternates for East Asian codepoints,
-        but Western fonts typically lack any vertical typesetting features.)
+        but Western fonts typically lack any vertical typesetting features
+        and East Asian fonts typically lack vertical substitutions for Western codepoints.)
         Unicode published draft data on which <i>characters</i> should appear sideways
         as the SVO property in <a href="http://www.unicode.org/reports/tr50/tr50-6.Orientation.txt">this data file</a>;
         however, this property has been abandoned for the current revision of [[!UTR50]].
+
+      <p><i>Characters</i> which are classified as <code>Tr</code> or <code>Tu</code> in [[!UTR50]]
+      are expected to have alternate glyphs or positioning for typesetting upright in vertical text.
+      In the case of <code>Tr</code> <i>characters</i>,
+      if such vertical alternate glyphs are missing from the font,
+      the UA may (but is not required to)
+      fall back to <a href="#typeset-sideways">typesetting them sideways</a>
+      in order to synthesize the missing glyphs.
+
     <dt id='typeset-sideways'>sideways characters 
     <dd>
       Are typeset rotated 90&deg; sideways with horizontal metrics,