[css-text-4] Add some issues for character text-align.

Author: dbaron

css-text-4/Overview.bs

@@ -749,6 +749,14 @@ Character-based Alignment in a Table Column</h3>
 	shifted accordingly. (Note that the strings do not have to be the same
 	for each cell, although they usually are.)
 
+	<p class="issue">Is this intended to say that it's the centers
+	of the alignment characters that should be aligned?
+	It's not clear that's what it says,
+	but that (or a different behavior) needs to be specified,
+	to describe what happens
+	when different occurrences of the alignment character
+	are in different fonts.</p>
+
 	<div class="example">
 
 		The following style sheet:
@@ -834,13 +842,81 @@ Character-based Alignment in a Table Column</h3>
 	in a cell at all, the string is aligned as if the alignment character had
 	been inserted at the end of its contents.
 
+	<p class="issue">This needs to specify what text is searched
+	for the alignment character.
+	Is it only in-flow text whose containing block is the cell?
+	Or is text within any in-flow descendants
+	in the block formatting context established by the cell considered?
+	If so, is it considered only as long as its text-align property
+	is consistent with the cell's?
+	(Consistent in the alignment character, or fully consistent?)</p>
+
+	<p class="issue">This behavior of aligning as though
+	the alignment character had been inserted at the end of
+	the contents of the cell, 
+	combined with center-of-character alignment,
+	will produce gaps on the end-side of any replaced elements
+	that are alone on a line with &lt;string&gt; text-alignment.
+	This is probably undesirable.</p>
+
+	<p class="issue">When the alignment character is inserted at
+	the end of the contents, which font is used?
+	(In particular, if the alignment character might be within
+	a descendant block, is it the font of the block or
+	the font of the table cell?
+	Or if the insertion is at a forced break within an inline,
+	does it use the font of the inline or the font of the block or cell?)
+	</p>
+
 	Character-based alignment occurs before table cell width computation so
 	that auto width computations can leave enough space for alignment.
 	Whether column-spanning cells participate in the alignment prior to
 	or after width computation is undefined.
 	If width constraints on the cell contents prevent full alignment
 	throughout the column, the resulting alignment is undefined.
 
+	<p class="issue">This should have a formal definition
+	of how character alignment affects
+	the min-content and max-content intrinsic widths
+	(of table columns and all content that can be inside table columns).
+	Max-content intrinsic widths need to be split
+	into three numbers (assuming that it's the centers of the
+	alignment character that are aligned): 
+	one for widths without alignment characters,
+	one for widths on the inline-start side
+	of the center of the alignment character,
+	one for widths on the inline-end side
+	of the center of the alignment character.
+	This operates based on all segments of text
+	between forced breaks for max-content widths.
+	For min-content widths, segments of text between forced breaks
+	that contain optional breaks within them should clearly contribute
+	only to the without-alignment-character width.
+	However, it's less clear
+	whether all min-content widths should work this way,
+	or whether segments between forced breaks
+	that do not have optional breaks
+	(and perhaps only those that actually contain the alignment character)
+	should contribute to start-side-of-alignment-character
+	and end-side-of-alignment-character min-content widths instead;
+	this choice is a tradeoff between the meaning of min-content
+	sizing of a table meaning the narrowest reasonable size versus
+	honoring alignment characters in more cases.
+	Another option might be to use whether line-breaking of optional breaks
+	is allowed as a control for which behavior to use.</p>
+	
+	<p class="issue">Formally defining the intrinsic width contributions
+	of column-spanning cells with &lt;string&gt; values of
+	text-align is a complicated (although straightforward) extension
+	of the decisions made for intrinsic width contributions
+	of non-column-spanning cells;
+	this should also be formally defined.
+	Contributions end up being made to the split intrinsic widths
+	of the startmost or endmost column (whichever is used for alignment),
+	and to the without-alignment-character intrinsic widths
+	of the other spanned columns.</p>
+
+
 
 <h2 id="spacing">
 Spacing</h2>