diff --git a/Modules/Applications/AppClassification/include/otbTrainImagesBase.txx b/Modules/Applications/AppClassification/include/otbTrainImagesBase.txx
index 93605b280744eb6ffdb89afc46b2d1b35a5a0df7..325d3b9c38b658755999af8d7626293f571e22c8 100644
--- a/Modules/Applications/AppClassification/include/otbTrainImagesBase.txx
+++ b/Modules/Applications/AppClassification/include/otbTrainImagesBase.txx
@@ -101,7 +101,10 @@ void TrainImagesBase::ShareSamplingParameters()
   //ShareParameter("sample.mim","rates.mim");
   ShareParameter( "ram", "polystat.ram" );
   ShareParameter( "elev", "polystat.elev" );
-  ShareParameter( "sample.vfn", "polystat.field" );
+  ShareParameter( "sample.vfn", "polystat.field",
+    "Field containing the class integer label for supervision" ,
+    "Field containing the class id for supervision. "
+      "The values in this field shall be cast into integers.");
 }
 
 void TrainImagesBase::ConnectSamplingParameters()
diff --git a/Modules/Applications/AppClassification/include/otbTrainVectorBase.txx b/Modules/Applications/AppClassification/include/otbTrainVectorBase.txx
index 380dfd6f5ecb8672ce047d03158bb468ba635962..e24c4165de2b6a1b1bf57c672e5ec69a1ef825a2 100644
--- a/Modules/Applications/AppClassification/include/otbTrainVectorBase.txx
+++ b/Modules/Applications/AppClassification/include/otbTrainVectorBase.txx
@@ -67,8 +67,9 @@ void TrainVectorBase::DoInit()
   SetDefaultParameterInt( "valid.layer", 0 );
 
   // Add class field if we used validation
-  AddParameter( ParameterType_ListView, "cfield", "Field containing the class id for supervision" );
+  AddParameter( ParameterType_ListView, "cfield", "Field containing the class integer label for supervision" );
   SetParameterDescription( "cfield", "Field containing the class id for supervision. "
+          "The values in this field shall be cast into integers. "
           "Only geometries with this field available will be taken into account." );
   SetListViewSingleSelectionMode( "cfield", true );