diff --git a/GIS-data-export.md b/GIS-data-export.md
index 17cc233..51b9cc4 100644
--- a/GIS-data-export.md
+++ b/GIS-data-export.md
@@ -53,4 +53,8 @@ To create a political/religious/provinces/culture/etc. map use _Vector_ -> _Geop
 
 Note that QGIs automatically turns a polygon layer into a multipolygon layer for this.
 
-Simply repeat this step for all the layers that you want to use (once for states, once for provinces, etc.). This will give you one layer in QGIS per attribute, and you can then style and hide/show the layers as needed.
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+Simply repeat this step for all the layers that you want to use (once for states, once for provinces, etc.). This will give you one layer in QGIS per attribute, and you can then style and hide/show the layers as needed.
+
+# Editing in QGIS
+
+When working with cells, you need to make sure that neighbor cells are changed as well, to prevent overlaps or gaps. QGIS supports topological editing for this, here is how to enable it: https://gis.stackexchange.com/questions/302965/how-can-i-enable-topological-editing-in-qgis-3
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