diff --git a/wsgi.py b/wsgi.py
index 792cb4b..15ef472 100644
--- a/wsgi.py
+++ b/wsgi.py
@@ -54,6 +54,12 @@ def plot(
     alpha: float | None = None,
 ) -> str:
     data_dict = {}
+
+    ## Important: If multiple results are stored for the same date
+    ##            the last is used. So this relies on the Landesbezirk data
+    ##            to be stored with a filename that is lexigraphically larger
+    ##            than the single district results.
+
     for f in sorted(Path(data_folder).iterdir()):
         with f.open("rb") as ff:
             df = pd.read_excel(ff, sheet_name=sheet_name)