[css-text-4] Revisions to word-boundary-expansion based on review by fantasai

Author: frivoal

css-text-4/Overview.bs

@@ -150,7 +150,7 @@ Detecting Word Boundaries: the 'word-boundary-detection' property</h4>
 			Otherwise,
 			the User Agent must insert the ZERO WIDTH SPACE (U+200B) character
 			at each detected word boundary
-			within the [=text node=] children of this element.
+			within the [=text run=] children of this element.
 			However, the UA must not insert U+200B:
 			* at the beginning or end of a [=block container=]
 			* at the beginning or end of an [=inline box=] whose parent box has a [=used value=] of ''word-boundary-detection/manual''
@@ -217,15 +217,9 @@ Makig Word Boundaries Visible: the 'word-boundary-expansion' property</h4>
 	to turn visible “spaces” such as the ETHIOPIC WORD SPACE (U+1361)
 	into an ordinary SPACE (U+0020).
 
-	This property enables all instances of U+200B ZERO WIDTH SPACE
-	to be replaced by the specified character.
-	Instances of <{wbr}> are considered equivalent to U+200B,
-	and are also replaced,
-	as are U+200B inserted by ''word-boundary-detection: auto()''.
-	This substitution happens before layout,
-	so all layout operations that depend on the characters in the content
-	(such as [[CSS-TEXT-3#white-space-rules]], [=line breaking=], or [=intrinsic sizing=])
-	must use that character instead of the original U+200B.
+	This property allows transforming certain word-separating characters
+	into other word-separating characters,
+	to accomodate variant typesetting styles.
 
 	<dl dfn-for="zero-width-space-expansion" dfn-type="value">
 		<dt><dfn>none</dfn>
@@ -234,16 +228,25 @@ Makig Word Boundaries Visible: the 'word-boundary-expansion' property</h4>
 		<dt><dfn>space</dfn>
 		<dd>
 			All instances of U+200B ZERO WIDTH SPACE
-			within the [=text node=] children of this element
+			within the [=text run=] children of this element
 			are replaced by U+0020 SPACE.
 
 		<dt><dfn>ideographic-space</dfn>
 		<dd>
 			All instances of U+200B ZERO WIDTH SPACE
-			within the [=text node=] children of this element
+			within the [=text run=] children of this element
 			are replaced by U+3000 IDEOGRAPHIC SPACE.
 	</dl>
 
+	Instances of <{wbr}> are considered equivalent to U+200B,
+	and are also replaced,
+	as are U+200B inserted by ''word-boundary-detection: auto()''.
+	Unlike 'text-transform',
+	this substitution happens before [[CSS-TEXT-3#white-space-phase-1]]
+	so that later operations that depend on the characters in the content
+	(including [[CSS-TEXT-3#white-space-rules]], [=line breaking=], and [=intrinsic sizing=])
+	use that character instead of the original U+200B.
+
 	Like 'text-transform', this property transforms text for styling purposes.
 	It has no effect on the underlying content,
 	and must not affect the content of a plain text copy &amp; paste operation.