diff --git a/LEGO1/tgl/tgl.h b/LEGO1/tgl/tgl.h
index 0fe0e7dc..5dec4a56 100644
--- a/LEGO1/tgl/tgl.h
+++ b/LEGO1/tgl/tgl.h
@@ -303,6 +303,8 @@ class Group : public Object {
     virtual Result  SetOrientation(const double direction[3],
                                    const double up[3]) = 0;
 #endif
+	// TODO: The type was changed from `FloatMatrix` to `Matrix` to make code in UpdateWorldData match.
+	// However, this is unlikely to be correct and will have to be figured out at some point.
 	virtual Result SetTransformation(const Matrix4&) = 0;
 
 	// ??? not yet fully implemented