diff --git a/Documentation/Examples/vertical_EAS.cc b/Documentation/Examples/vertical_EAS.cc
index 323bf7b549281d883bd66b0f1fb300953e4713d5..d78c72f42288559fe3f749aecd16f8d912093255 100644
--- a/Documentation/Examples/vertical_EAS.cc
+++ b/Documentation/Examples/vertical_EAS.cc
@@ -194,8 +194,11 @@ int main(int argc, char** argv) {
   tracking_line::TrackingLine tracking;
   cascade::Cascade EAS(env, tracking, sequence, stack);
   EAS.Init();
+
+  // to fix the point of first interaction, uncomment the following two lines:
   //  EAS.SetNodes();
   //  EAS.forceInteraction();
+
   EAS.Run();
 
   eLoss.PrintProfile(); // print longitudinal profile