diff --git a/Use-Cases.md b/Use-Cases.md
index 2331870..604aa80 100644
--- a/Use-Cases.md
+++ b/Use-Cases.md
@@ -36,6 +36,8 @@ This alternative can be implemented if the layer knows the map projection.  The
 
 _Questions from Eric:_
 
+How do we know that the transform's source projection is EPSG:4326? It's not specified anywhere in the application code.
+
 Why does the layer need to know about the map/view projection for implementing this? The layer renderer knows about the map/view projection, so it can be the one providing the projection.
 
 ### Generate features in app and add to a layer