[css-text-4] add preserve-auto and preserve-trim, explain the shorthand

Author: frivoal

css-text-4/Overview.bs

@@ -36,7 +36,7 @@ White Space Collapsing: the 'text-space-collapse' property</h3>
 
 	<pre class="propdef">
 	Name: text-space-collapse
-	Value: collapse | discard | preserve | preserve-breaks | preserve-spaces 
+	Value: collapse | discard | preserve | preserve-auto | preserve-trim | preserve-breaks | preserve-spaces
 	Initial: collapse
 	Applies to: all elements
 	Inherited: yes
@@ -65,6 +65,26 @@ White Space Collapsing: the 'text-space-collapse' property</h3>
 			from collapsing sequences of white space.
 			<a>Segment breaks</a> are preserved as forced line breaks.
 
+		<dt><dfn>preserve-auto</dfn>
+		<dd>
+			This value preserves white space and <a>segment breaks</a> as for ''preserve''.
+			However, the UA <em>may</em> visually collapse
+			the advance widths of preserved white space
+			that occur at the end of a line.
+
+			If 'text-wrap' is ''text-wrap/normal'' or ''text-wrap/balance'',
+			whether or not there are soft wrap opportunities
+			in preserved sequences of white space,
+			and if yes where and under what condition,
+			is UA defined.
+
+		<dt><dfn>preserve-trim</dfn>
+		<dd>
+			This value preserves white space and <a>segment breaks</a> as for ''preserve''.
+			However, the UA <em>must</em> visually collapse to 0
+			the advance widths of all preserved white space
+			that occur at the end of a line.
+
 		<dt><dfn>preserve-breaks</dfn>
 		<dd>
 			This value collapses white space as for ''collapse'', but preserves
@@ -450,6 +470,52 @@ Shorthand for White Space and Wrapping: the 'white-space' property</h2>
 	Note: This shorthand combines both inheritable and non-inheritable properties.
 	If this is a problem, please inform the CSSWG.
 
+	The following table gives the mapping of the values of the shorthand to its longhands.
+
+	<table class="data">
+		<colgroup class="header"></colgroup>
+		<colgroup span=3></colgroup>
+		<thead>
+			<tr>
+				<th>'white-space'
+				<th>'text-space-collapse'
+				<th>'text-wrap'
+				<th>'text-space-trim'
+		</thead>
+		<tbody>
+		<tr>
+			<th>''white-space/normal''
+			<td>''text-space-collapse/collapse''
+			<td>''text-wrap/normal''
+			<td>''text-space-trim/none''
+		<tr>
+			<th>''pre''
+			<td>''text-space-collapse/preserve''
+			<td>''text-wrap/nowrap''
+			<td>''text-space-trim/none''
+		<tr>
+			<th>''nowrap''
+			<td>''text-space-collapse/collapse''
+			<td>''text-wrap/nowrap''
+			<td>''text-space-trim/none''
+		<tr>
+			<th>''pre-wrap''
+			<td>''text-space-collapse/preserve''
+			<td>''text-wrap/normal''
+			<td>''text-space-trim/none''
+		<tr>
+			<th>''pre-wrap-auto''
+			<td>''text-space-collapse/preserve-auto''
+			<td>''text-wrap/normal''
+			<td>''text-space-trim/none''
+		<tr>
+			<th>''pre-line''
+			<td>''text-space-collapse/preserve-breaks''
+			<td>''text-wrap/normal''
+			<td>''text-space-trim/none''
+		</tbody>
+	</table>
+
 	Issue: Add details from level 3
 
 <h2 id="hyphenation">