diff --git a/tests/chained_requests.py b/tests/chained_requests.py
index 39a1e35..dc3a8c6 100644
--- a/tests/chained_requests.py
+++ b/tests/chained_requests.py
@@ -42,6 +42,7 @@ class Layer:
     def __init__(self, layer_data):
         try:
             self.extra = layer_data["metadata_decoded"]["extra_fields"]
+            self.layer_number = self.extra["Layer Progressive Number"]["value"] # integer
             self.target_elabid = self.extra["Target"]["value"] # elabid
             self.rheed_system_elabid = self.extra["RHEED System"]["value"] # elabid
             self.laser_system_elabid = self.extra["Laser System"]["value"] # elabid