diff --git a/css-values-4/Overview.bs b/css-values-4/Overview.bs
index 99a423c80438..dbdc028da747 100644
--- a/css-values-4/Overview.bs
+++ b/css-values-4/Overview.bs
@@ -2045,12 +2045,12 @@ The Large, Small, and Dynamic Viewport Sizes</h5>
 	* Changes in interface that happen as a result of scrolling
 		or other frequent page interactions that would disturb the user
 		if they resulted in substantial layout changes
-		must be categorized as the former (A).
+		must be categorized as the latter (B).
 
 	* Changes in interface that have a sufficiently steady state
 		that re-laying out the document into the adjusted space
 		would be beneficial to the user
-		must be categorized as the latter (B).
+		must be categorized as the former (A).
 
 	* Additionally,
 		UAs may have some dynamically-shown interfaces
@@ -5192,6 +5192,13 @@ Recent Changes</h3>
 
 	(This is a subset of [[#additions-L3]].)
 
+	Substantial since <a href="https://www.w3.org/TR/2021/WD-css-values-4-20211016/">16 October 2021 WD</a>:
+
+	<ul>
+		<li>Fixed the inverted assignment of [=viewport-percentage length=] behaviors
+		to types of interface changes (A vs. B).
+	</ul>
+
 	Substantial since <a href="https://www.w3.org/TR/2021/WD-css-values-4-20210930/">30 September 2021 WD</a>:
 
 	<ul>