[css-writing-modes] Add integer values of glyph-orientation-vertical. Clarify that other values (and glyph-orientation-horizontal) must be treated as invalid. See SVGWG minutes from Thursday.

Author: fantasai

css-writing-modes/Overview.bs

@@ -1381,7 +1381,7 @@ Obsolete: the SVG1.1 'glyph-orientation-vertical' property</h4>
 
   <pre class='propdef'>
   Name: glyph-orientation-vertical
-  Value: auto | 0deg | 90deg
+  Value: auto | 0deg | 90deg | 0 | 90
   Initial: n/a
   Applies to: n/a
   Inherited: na/
@@ -1393,9 +1393,12 @@ Obsolete: the SVG1.1 'glyph-orientation-vertical' property</h4>
   </pre>
 
   Some SVG user agents will need to process documents containing
-  the obsolete SVG 'glyph-orientation-vertical' property.
-  It is recommended that such UAs treat 'glyph-orientation-vertical'
-  as a shorthand alias of 'text-orientation' as follows:
+  the obsolete SVG 'glyph-orientation-vertical' property,
+  which was defined to accept an ''glyph-orientation-vertical/auto'' keyword
+  as well as <<angle>> and <<integer>> values representing multiples of 90&deg;.
+  While supporting this property is <em>optional</em>,
+  UAs that do so must alias 'glyph-orientation-vertical'
+  as a shorthand of 'text-orientation' as follows:
 
   <table class="data">
     <thead>
@@ -1409,14 +1412,29 @@ Obsolete: the SVG1.1 'glyph-orientation-vertical' property</h4>
       <tr>
         <td>''0deg''
         <td>''upright''
+      <tr>
+        <td>''0''
+        <td>''upright''
       <tr>
         <td>''90deg''
         <td>''sideways''
+      <tr>
+        <td>''90''
+        <td>''sideways''
   </table>
 
-  Note: The ''180deg'' and ''270deg'' values
+  UAs must ignore and treat as invalid
+  any other values for the 'glyph-orientation-vertical' property;
+  and treat as invalid the 'glyph-orientation-horizontal' property
+  in its entirety.
+
+  Note: The ''180deg'' and ''270deg'' values,
+  the radian and gradian values,
   and the 'glyph-orientation-horizontal' property
-  are not mapped because they have no known use cases.
+  are not mapped because they have no known use cases
+  nor significant amounts of dependent content,
+  and are therefore not part of CSS,
+  and have been likewise dropped from SVG.
 
 <h2 id="abstract-box">
 Abstract Box Terminology</h2>