diff --git a/Use-Cases.md b/Use-Cases.md
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@@ -111,3 +111,7 @@ Some data are represented most compactly as vector features.  It should be possi
 ### Markers and labels maintain orientation even when the map is rotated
 
 Map rotation is useful, for example so that "up" corresponds to the direction in which the user is moving.  However, labels and markers should not rotate with the map, and should instead always be aligned horizontally.
+
+### Sub-feature styling
+
+The user wishes to style a feature, e.g. a line string, according to some value that varies across the feature.  It should be possible to "sub-style" a feature, e.g. to vary the color of a GPS tracklog by the speed of movement at that point.
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