diff --git a/LDDsimulation/domainSubstructuring.py b/LDDsimulation/domainSubstructuring.py
index 2a3de3b6e4a11117a2b504aa7ac799a007075547..bf9c7aa7f323fff2cd7ed73164a48da5e96e181d 100644
--- a/LDDsimulation/domainSubstructuring.py
+++ b/LDDsimulation/domainSubstructuring.py
@@ -1,4 +1,4 @@
-"""Class domainSubstructuring, Copyright 2020, David Seus
+"""Class domainSubstructuring and example substructurings, Copyright 2020, David Seus
 
 Provides the base class and example classes for domain substructurings used
 for LDD simulations within the LDDsimulation class.
diff --git a/Usecases/README.md b/Usecases/README.md
index d8aa96ba29f0b07aaae1bd26b1afa90a569daa06..d583c84b4c3b4c15705c815d3d2af9ee3f3dd011 100644
--- a/Usecases/README.md
+++ b/Usecases/README.md
@@ -273,6 +273,15 @@ adjacent_subdomains = substructuring.adjacent_subdomains
 subdomain_def_points = substructuring.subdomain_def_points
 outer_boundary_def_points = substructuring.outer_boundary_def_points
 ~~~
+This block sets the domain of simulation and its subdomain substructuring.
+In this block you only need to change the line
+~~~
+substructuring = dss.twoSoilLayers()
+~~~
+This block calls constructors of substructurings. These are classes defined in
+`../LDDsimulation/domainSubstructuring.py`.
+If you want to define your own substructurings have a look in that file.
+Some explantion is given in that file on how to define substructuring classes. 
 
 ### MODEL CONFIGURATION
 ~~~python