Code_FAQ.md

+Modify a model programmatically
+===============================
+
+Say you want to do:
+
+    myModel.setParameter(42);
+
+Then you should actually write:
+
+    ITopLevelElement modelContext = IPersistencyService.getInstance().getTopLevelElementFor(modelElement);
+    modelContext.runAsCommand(() ->
+      myModel.setParameter(42)
+    ));
+