Prevent Zero Length skybox bouncing

docs/PORTING.md

@@ -304,6 +304,11 @@ random outcome using its effective one-in-seven grammar weight. Zero Length
 freezes an Age at its generated phase without changing the global daylight
 cycle, while nonzero Ages retain their independently scaled clocks.
 
+Version 0.2.20.2 gives Zero Length Ages a stationary per-dimension clock rate
+instead of advancing and correcting their time once per tick. This keeps the
+integer day time fixed while preventing the client skybox from visually
+bouncing between adjacent celestial positions.
+
 Version 0.2.14.0 restores the legacy Linking and Descriptive Book artwork for
 inventory items and gives each book its matching open-book texture when placed
 on a Book Stand. Return Linking Books created inside another Age also retain and