diff --git a/test/rendering/cases/layer-vector-decluttering-extended/main.js b/test/rendering/cases/layer-vector-decluttering-extended/main.js
index 821174ec20..423fdbc8e7 100644
--- a/test/rendering/cases/layer-vector-decluttering-extended/main.js
+++ b/test/rendering/cases/layer-vector-decluttering-extended/main.js
@@ -27,8 +27,8 @@ sourceBlue.addFeatures([
     text: 'top-blue',
   }),
 ]);
-// circles are always drawn, but serve as obstacles,
-// texts are decluttered against each other and the circles
+// on-top blue circle.
+// shows that objects (red layer) will not serve as obstacles for layers on-top.
 map.addLayer(
   new VectorLayer({
     zIndex: 4,
@@ -70,8 +70,10 @@ sourceRed.addFeatures([
     text: 'e-red',
   }),
 ]);
-// circles are always drawn, but serve as obstacles,
-// texts are decluttered against each other and the circles
+// red circles are always drawn, but serve as obstacles.
+// however, they cannot serve as obstacles for layers on-top (blue layer).
+// texts are decluttered against each other and the circles.
+// circles are drawn on non-declutter executor, i.e. behind decluttered labels and objects.
 map.addLayer(
   new VectorLayer({
     zIndex: 3,
@@ -113,8 +115,8 @@ sourceOrange.addFeatures([
     text: 'e-orange',
   }),
 ]);
-// circles are always drawn,
-// texts are decluttered against each other and the layer 1 circles/texts
+// orange circles are always drawn.
+// texts are decluttered against each other and the blue/red layer circles/texts.
 map.addLayer(
   new VectorLayer({
     zIndex: 2,
@@ -156,10 +158,10 @@ sourceCyan.addFeatures([
     text: 'e-cyan',
   }),
 ]);
-// circles are always drawn
-// texts are decluttered against each others (and layers 1/2)
-// the circles of layer 2 and this layer are no obstactles for texts
-// the texts are decluttered and thus above the circles of layer 2
+// cyan circles are always drawn.
+// texts are decluttered against each others (and blue/red/orange layers).
+// the circles of the orange layer and this layer are no obstactles for texts.
+// the texts are decluttered and thus above the circles of the orange layer.
 map.addLayer(
   new VectorLayer({
     zIndex: 1,