Index: DamClients/DamPythonInterface/trunk/src/dampythoninterface/input.py
===================================================================
diff -u -r3499 -r3500
--- DamClients/DamPythonInterface/trunk/src/dampythoninterface/input.py	(.../input.py)	(revision 3499)
+++ DamClients/DamPythonInterface/trunk/src/dampythoninterface/input.py	(.../input.py)	(revision 3500)
@@ -20,7 +20,7 @@
 # All rights reserved.
 
 
-from typing import List
+from typing import List, Optional
 from pathlib import Path
 import lxml.etree as et
 from pydantic import validator
@@ -43,7 +43,7 @@
 
     SurfaceLines: List[SurfaceLine] = []
     Soils: List[Soil] = []
-    StabilityParameters: StabilityParameters = StabilityParameters()
+    StabilityParameters: Optional[StabilityParameters]
     SoilProfiles1D: List[SoilProfile1D] = []
     Segments: List[Segment] = []