diff --git a/product/ERP5/interfaces/trade_model_path.py b/product/ERP5/interfaces/trade_model_path.py
index c237f8581831ecedbf4ece1d70998e7e01e74f9e..ef6be7ef0aa70608e346a6a21b12231a5955a096 100644
--- a/product/ERP5/interfaces/trade_model_path.py
+++ b/product/ERP5/interfaces/trade_model_path.py
@@ -35,12 +35,9 @@ from zope.interface import Interface
 class ITradeModelPath(Interface):
   """Trade Model Path interface specification
 
-  ITradeModelPath provides a method to calculate the completion
-  date of existing movements based on business path properties.
-  It also provides methods to determine whether all related simulation
-  movements related to a given explanation are completed, partially
-  completed or frozen. Finally, it provides a method to invoke
-  delivery builders for all movements related to a given explanation.
+  The core purpose of Trade Model Path is to define the arrows and dates of 
+  an amount generated by a Rule and eventually transform this amount into a 
+  single or multiple similation movements.
   """
 
   def getExpectedQuantity(amount):