[css-align] Better define the conditions of baseline synthesis when baseline-aligning. Fixes #721.

tabatkins · tabatkins · commit e1b0f2dcdc13 · 2017-02-02T12:51:06.000-08:00
diff --git a/css-align/Overview.bs b/css-align/Overview.bs
@@ -1574,23 +1574,27 @@ Baseline Alignment Terminology</h3>
 
 	</ul>
 
-	The <a>baseline alignment preferences</a> of two boxes are compatible if they have the same <a>block flow direction</a> and <a>baseline alignment preference</a>,
-	or have opposite <a>block flow direction</a> and opposite <a>baseline alignment preference</a>.
-	For this purpose, boxes that establish an <a>orthogonal flow</a>
-	are treated as having the same <a>block flow direction</a>
-	as their <a>alignment context</a>,
+	The <a>baseline alignment preferences</a> of two boxes in a <a>baseline-sharing group</a> are compatible if they have:
+
+	* the same <a>block flow direction</a> and <a>baseline alignment preference</a>
+	* opposite <a>block flow direction</a> and opposite <a>baseline alignment preference</a>
+
+	For this purpose, boxes whose <a>block flow direction</a> is parallel to the <a>alignment context</a>’s axis
+	are treated as having a <a>block flow direction</a>
+	orthogonal to the <a>alignment context’s</a> axis
+	and directed end-ward relative to the box that establishes the <a>alignment context</a>,
 	and their baselines are <a>synthesized</a> accordingly,
 	exactly as for replaced elements and other boxes that have no <a>natural baseline</a>.
 
 
 	Boxes share an <dfn lt="shared alignment context|alignment context" export>alignment context</dfn> along a particular axis when they are:
 
 	<ul>
-		<li>table cells in the same row, along the table's row (inline) axis
-		<li>table cells in the same column, along the table's column (block) axis
-		<li>grid items in the same row, along the grid's row (inline) axis
-		<li>grid items in the same column, along the grid's colum (block) axis
-		<li>flex items in the same flex line, along the flex container's main axis
+		<li>table cells in the same row, along the table's row (inline) axis, established by the row box
+		<li>table cells in the same column, along the table's column (block) axis, established by the column box
+		<li>grid items in the same row, along the grid's row (inline) axis, established by the <a>grid container</a>
+		<li>grid items in the same column, along the grid's colum (block) axis, established by the <a>grid container</a>
+		<li>flex items in the same flex line, along the flex container's main axis, established by the <a>flex container</a>
 	</ul>
 
 	Note: Conceptually,
