diff --git a/yaml/copy_columns.yaml b/yaml/copy_columns.yaml
index 2b59bba..65c2f00 100644
--- a/yaml/copy_columns.yaml
+++ b/yaml/copy_columns.yaml
@@ -10,4 +10,10 @@ operations:
     y: 0
     z: 0
 
+  - name: Show diff between source and result
+    command: diff
+    input: ifc/office_level_0.ifc
+    output: office_level_columns.diff
+    verbose: true
+
 dest: ifc/office_level_columns.ifc