[css-ruby] Allow UAs to support spanning via magic.

--HG--
extra : rebase_source : 41c0da50da62faf46aa5269a01642aebd6cbb212

Author: fantasai

css-ruby/Overview.html

@@ -607,6 +607,9 @@ <h3 id=pairing><span class=secno>2.3. </span> Ruby Pairing and Annotation
       annotations</i></a> are assumed to be associated with empty, anonymous
       bases inserted at the end of the <a
       href="#ruby-base-container-box"><i>ruby base container</i></a>.
+      <p>If an implementation supports ruby markup with explicit spanning
+       (e.g. XHTML Complex Ruby Annotations), it must adjust the pairing
+       rules to pair spanning annotations to multiple bases appropriately.
     </ol>
 
     <p>A this point, ruby “columns” are defined, each represented by a

css-ruby/Overview.src.html

@@ -342,6 +342,11 @@ <h3 id="pairing">
 		If there are not enough <i>ruby bases</i>,
 		any remaining <i>ruby annotations</i> are assumed to be associated
 		with empty, anonymous bases inserted at the end of the <i>ruby base container</i>.
+
+		<p>If an implementation supports ruby markup with explicit spanning
+		(e.g. XHTML Complex Ruby Annotations),
+		it must adjust the pairing rules to pair spanning annotations to multiple bases
+		appropriately.
 	</ol>
 
 	<p>A this point, ruby “columns” are defined,