From 67ba993a32386b185cdfa8eedcd0651bc3424dce Mon Sep 17 00:00:00 2001
From: Colin Blackburn <colb@bgs.ac.uk>
Date: Fri, 30 Jun 2023 15:34:13 +0100
Subject: [PATCH] Add comment

---
 app/routes.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/app/routes.py b/app/routes.py
index 24f2420..305a425 100644
--- a/app/routes.py
+++ b/app/routes.py
@@ -398,7 +398,8 @@ def ags_export_by_polygon(polygon: str = polygon_query):
     :raises HTTPException 500: If the borehole exporter returns an error.
     """
 
-    # Check that the WKT is a valid POLYGON
+    # Check explicitly that the WKT is a valid POLYGON
+    # The BOREHOLE_INDEX_URL API does not return an error for some bad WKT
     check_df = gpd.GeoDataFrame([{"type": "zone", "bound": polygon}])
     try:
         gpd.GeoSeries.from_wkt(check_df['bound'])