[css-text-4] add multi-line for issue 672

Author: astearns

css-text-4/Overview.bs

@@ -175,7 +175,7 @@ Text Wrap Settings: the 'text-wrap' property</h3>
 
 	<pre class="propdef">
 	Name: text-wrap
-	Value: wrap | nowrap | balance
+	Value: wrap | nowrap | balance | multi-line
 	Initial: wrap
 	Applies to: all elements
 	Inherited: yes
@@ -196,6 +196,10 @@ Text Wrap Settings: the 'text-wrap' property</h3>
 			for the WJ, ZW, and GL line-breaking classes
 			in [[!UAX14]] must be honored.
 
+			The exact algorithm is UA-defined.
+			The algorithm may consider multiple lines when making break decisions.
+			The UA may bias for speed over best layout.
+
 		<dt><dfn>nowrap</dfn>
 		<dd>
 			Lines may not break; text that does not fit within the block container
@@ -217,14 +221,23 @@ Text Wrap Settings: the 'text-wrap' property</h3>
 			is that which remains after placing floats and inline content,
 			but before any adjustments due to text justification.
 			Line boxes are balanced when the standard deviation
-			from the average <a>inline-size</a> of the remaining space in eacn line box
+			from the average <a>inline-size</a> of the remaining space in each line box
 			is reduced over the block
 			(including lines that end in a forced break).
 
 			The exact algorithm is UA-defined.
 
 			UAs may treat this value as ''text-wrap/wrap'' if there are more than ten lines to balance.
 
+		<dt><dfn>multi-line</dfn>
+		<dd>
+			Same as ''text-wrap/wrap'' for inline-level elements.
+			Same as ''text-wrap/wrap'' for block-level elements,
+			except as below.
+
+			The exact algorithm is UA-defined.
+			The algorithm should consider multiple lines when making break decisions.
+			The UA should bias for best layout over speed.
 	</dl>
 
 	Regardless of the 'text-wrap' value,
@@ -251,6 +264,24 @@ Text Wrap Settings: the 'text-wrap' property</h3>
 
 	<!-- add a sample prioritization algorithm -->
 
+	Note: The ''text-wrap/wrap'' value is intended 
+	for speedy legacy line breaking, 
+	which has so far used first-fit/greedy algorithms 
+	that can often give sub-optimal results. 
+	UAs could experiment with better line breaking algorithms 
+	with this default value, 
+	but optimal results will probably take more time. 
+	The ''text-wrap/multi-line'' and ''text-wrap/balance'' values 
+	are intended as opt-in choices to take more time for better results. 
+	The ''text-wrap/balance'' value is intended for titles and captions, 
+	and the ''text-wrap/multi-line'' is intended for body text.
+
+	Note: Some line breaking algorithms can interact unexpectedly with editing.
+	Changing upstream line breaks on user edits can be unsettling.
+	As UAs experiment with better line breaking algorithms, 
+	we will likely need to add a property 
+	to constrain upstream changes while editing.
+
 <h3 id="wrap-before">
 Inline breaks between boxes: the 'wrap-before'/'wrap-after' properties</h3>
 
@@ -524,10 +555,9 @@ Hyphens: the 'hyphenate-character' property</h3>
 		</pre>
 	</div>
 
-	<p class="note">
-		Both hyphens triggered by automatic hyphenation and
-		hyphens triggered by soft hyphens are rendered according to
-		'hyphenate-character'.
+	Note: Both hyphens triggered by automatic hyphenation and
+	hyphens triggered by soft hyphens are rendered according to
+	'hyphenate-character'.
 
 <h3 id="hyphenate-size-limits">
 Hyphenation Size Limit: the 'hyphenate-limit-zone' property</h3>
@@ -582,9 +612,9 @@ Hyphenation Character Limits: the 'hyphenate-limit-chars' property</h3>
 	value means that the UA chooses a value that adapts to the current
 	layout.
 
-	<p class="note">Unless the UA is able to calculate a better value, it
-		is suggested that ''hyphenate-limit-chars/auto'' means 2 for before and after, and 5 for
-		the word total.
+	Note: Unless the UA is able to calculate a better value, it
+	is suggested that ''hyphenate-limit-chars/auto'' means 2 for before and after, and 5 for
+	the word total.
 
 	<div class="example">
 		In the example below, the minimum size of a hyphenated word is
@@ -801,12 +831,10 @@ Character-based Alignment in a Table Column</h3>
 			the cells' contents to either side of the axis).
 	</ul>
 
-	<p class="note">
-		Right alignment is used by default for character-based
-		alignment because numbering systems are almost all left-to-right even
-		in right-to-left writing systems, and the primary use case of
-		character-based alignment is for numerical alignment.
-	</p>
+	Note: Right alignment is used by default for character-based
+	alignment because numbering systems are almost all left-to-right even
+	in right-to-left writing systems, and the primary use case of
+	character-based alignment is for numerical alignment.
 
 	If the alignment character appears more than once in the text, the first
 	instance is used for alignment. If the alignment character does not appear
@@ -1069,18 +1097,17 @@ Fullwidth Punctuation Collapsing</h4>
 	For such proportional glyphs, the given advance width is considered
 	simultaneously full-width and half-width: no space is added or removed.
 
-	<p class="note">
-		The advance width of a standard Han character
-		can be determined either from font metrics
-		such as the OpenType <code>ideo</code> and <code>idtp</code> baselines for the opposite writing mode,
-		or by taking the advance width of a Han character such as 水 U+6C34.
-		(The opposite writing mode must be used because some fonts are compressed
-		so that the characters are not square.)
-		More information on OpenType metrics can be found
-		<a href="http://www.microsoft.com/typography/otspec/baselinetags.htm#ideoembox">in the OpenType spec</a>.
-		Note that if 水 U+6C34, 卜 U+535C, and 一 U+4E00 do not all have the same advance width,
-		the font has proportional ideographs
-		and the fullwidth advance width cannot be reliably determined by measuring glyphs.
+	Note: The advance width of a standard Han character
+	can be determined either from font metrics
+	such as the OpenType <code>ideo</code> and <code>idtp</code> baselines for the opposite writing mode,
+	or by taking the advance width of a Han character such as 水 U+6C34.
+	(The opposite writing mode must be used because some fonts are compressed
+	so that the characters are not square.)
+	More information on OpenType metrics can be found
+	<a href="http://www.microsoft.com/typography/otspec/baselinetags.htm#ideoembox">in the OpenType spec</a>.
+	Note that if 水 U+6C34, 卜 U+535C, and 一 U+4E00 do not all have the same advance width,
+	the font has proportional ideographs
+	and the fullwidth advance width cannot be reliably determined by measuring glyphs.
 
 	Unless 'text-spacing' is set to ''space-adjacent'' or ''text-spacing/none''
 	(or the font has proportional fullwidth punctuation glyphs),
@@ -1321,9 +1348,9 @@ Japanese Paragraph-start Conventions in CSS</h4>
 <h2 id="edge-effects">
 Edge Effects</h2>
 
-	<p class="note">Add final level 3 content</p>
+	Note: Add final level 3 content
 
 <h2 class="no-num" id="acknowledgements">
 Acknowledgements</h2>
 
-	<p class="note">Add final level 3 list, with Randy Edmunds and Florian Rivoal added</p>
+	Note: Add final level 3 list, with Randy Edmunds and Florian Rivoal added