[css-sizing-4] Note the driving principle behind sizing transfers.

w3c@ede56bd#commitcomment-40570230

Author: fantasai

css-sizing-4/Overview.bs

@@ -218,6 +218,12 @@ Intrinsic Aspect Ratios: the 'aspect-ratio' property</h3>
 		in the <var>destination</var> axis
 		as well as by the transferred minimum, if any.
 
+	Note: The basic principle is that sizing constraints
+	transfer through the aspect-ratio to the other side
+	to preserve the aspect ratio to the extent that they can
+	without violating any sizes specified explictly on that affected axis.
+	<!-- This is the principle that drove the contents of the table in CSS2 Section 10.4. -->
+
 	<div class="example">
 		This example sets each item in the grid to render as a square,
 		determining the number of items and their widths by the available space.