[css3-writing-modes] Clarifications to vertical typesetting

Author: fantasai

css3-writing-modes/Overview.html

@@ -1948,6 +1948,16 @@ <h4 id=vertical-orientations><span class=secno>5.1.1. </span> Mixed
    fall back to typesetting them sideways if the appropriate glyphs are
    missing.
 
+  <p> In some systems (e.g. when using OpenType fonts), to correctly orient a
+   <a href="#character"><i>character</i></a> belonging to the Mongolian or
+   Phags-pa script upright, the UA must actually typeset it <a
+   href="#typeset-sideways">sideways</a>.
+
+  <p class=note>This is because the "upright" orientation in the Unicode code
+   charts (which assume vertical typesetting) and the "upright" orientation
+   of the glyphs of these scripts in most OpenType fonts (which assume
+   horizontal typesetting) don't match.
+
   <p class=issue> As of the time of publication, Unicode has not yet
    officially updated its orientation data to account for the many errata
    that were accepted in June 2012. Therefore, the official UTR50 data
@@ -1966,14 +1976,14 @@ <h4 id=vertical-font-features><span class=secno>5.1.2. </span> Vertical
   <dl>
    <dt>upright characters
 
-   <dd> Are typeset with vertical font metrics. The UA must synthesize
-    vertical font metrics for fonts that lack them. (This specification does
-    not define heuristics for synthesizing such metrics.) Additionally, font
-    features (such as alternate glyphs) intended for use in vertical
-    typesetting must be used. (E.g. the OpenType ‘<code
-    class=css>vert</code>’ feature must be enabled.) Furthermore,
-    characters from horizontal cursive scripts (such as Arabic) are shaped in
-    their isolated forms when typeset upright.
+   <dd> Are typeset upright with vertical font metrics. The UA must
+    synthesize vertical font metrics for fonts that lack them. (This
+    specification does not define heuristics for synthesizing such metrics.)
+    Additionally, font features (such as alternate glyphs and other
+    transformation) intended for use in vertical typesetting must be used.
+    (E.g. the OpenType ‘<code class=css>vert</code>’ 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
@@ -1989,22 +1999,13 @@ <h4 id=vertical-font-features><span class=secno>5.1.2. </span> Vertical
      revisions of <a href="#UTR50"
      rel=biblioentry>[UTR50]<!--{{!UTR50}}--></a>.
 
-    <p> In some font systems (e.g. OpenType), to correctly render a <a
-     href="#character"><i>character</i></a> belonging to the Mongolian or
-     Phags-pa script upright, the UA must actually typeset it <a
-     href="#typeset-sideways">sideways</a>.
-
-    <p class=note>This is because the "upright" orientation in the Unicode
-     code charts (which assume vertical typesetting) and the "upright"
-     orientation of the glyphs of these scripts in most OpenType fonts (which
-     assume horizontal typesetting) don't match.
-
    <dt id=typeset-sideways>sideways characters
 
-   <dd> Are typeset with horizontal metrics, and vertical typesetting
-    features are not used. However, if the font has features meant to be
-    enabled for sideways text that is typeset in vertical lines (e.g. to
-    adjust brush stroke angles or alignment), those features are used.
+   <dd> Are typeset rotated 90° sideways with horizontal metrics, and
+    vertical typesetting features are not used. However, if the font has
+    features meant to be enabled for sideways text that is typeset in
+    vertical lines (e.g. to adjust brush stroke angles or alignment), those
+    features are used.
     <!--<p class="issue">Propose 'svrt' as an OpenType substitution feature
       that is applied to rotated horizontal text in vertical text runs,
       to handle these cases.-->

css3-writing-modes/Overview.src.html

@@ -1368,6 +1368,16 @@ <h4 id='vertical-orientations'>
     alternately it may check for such glyphs first,
     and fall back to typesetting them sideways if the appropriate glyphs are missing.
 
+  <p>
+    In some systems (e.g. when using OpenType fonts),
+    to correctly orient a <i>character</i> belonging to the Mongolian or Phags-pa script upright,
+    the UA must actually typeset it <a href="#typeset-sideways">sideways</a>.
+  <p class="note">This is because the "upright" orientation
+    in the Unicode code charts (which assume vertical typesetting)
+    and the "upright" orientation of the glyphs of these scripts
+    in most OpenType fonts (which assume horizontal typesetting)
+    don't match.
+
   <p class='issue'>
     As of the time of publication,
     Unicode has not yet officially updated its orientation data to account for the many errata that were accepted in June 2012.
@@ -1384,11 +1394,11 @@ <h4 id='vertical-font-features'>
   <dl>
     <dt>upright characters
     <dd>
-      Are typeset with vertical font metrics.
+      Are typeset upright with vertical font metrics.
       The UA must synthesize vertical font metrics for fonts that lack them.
       (This specification does not define heuristics for synthesizing such metrics.)
-      Additionally, font features (such as alternate glyphs) intended
-      for use in vertical typesetting must be used.
+      Additionally, font features (such as alternate glyphs and other transformation)
+      intended for use in vertical typesetting must be used.
       (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.
@@ -1404,19 +1414,9 @@ <h4 id='vertical-font-features'>
         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 future revisions of [[!UTR50]].
-      <p>
-        In some font systems (e.g. OpenType),
-        to correctly render a <i>character</i> belonging to the Mongolian or Phags-pa script upright,
-        the UA must actually typeset it <a href="#typeset-sideways">sideways</a>.
-      <p class="note">This is because the "upright" orientation
-        in the Unicode code charts (which assume vertical typesetting)
-        and the "upright" orientation of the glyphs of these scripts
-        in most OpenType fonts (which assume horizontal typesetting)
-        don't match.
-
     <dt id='typeset-sideways'>sideways characters 
     <dd>
-      Are typeset with horizontal metrics,
+      Are typeset rotated 90&deg; sideways with horizontal metrics,
       and vertical typesetting features are not used.
       However, if the font has features meant to be enabled
       for sideways text that is typeset in vertical lines