diff --git a/src/BOPAlgo/BOPAlgo_BOP.cdl b/src/BOPAlgo/BOPAlgo_BOP.cdl
index 3f2e37ad54..064e36883d 100644
--- a/src/BOPAlgo/BOPAlgo_BOP.cdl
+++ b/src/BOPAlgo/BOPAlgo_BOP.cdl
@@ -20,6 +20,7 @@ uses
     Shape from TopoDS,  
     BaseAllocator from BOPCol,  
     ListOfShape from BOPCol, 
+    ListOfShape from TopTools, 
     MapOfShape  from BOPCol,  
     IndexedDataMapOfShapeListOfShape from BOPCol,
     Operation from BOPAlgo, 
@@ -97,6 +98,14 @@ is
     returns Boolean from Standard
     is protected;
 
+    Generated (me:out;  
+        theS : Shape from TopoDS)
+    ---Purpose: Returns the  list of shapes generated from the
+    --          shape theS. 
+    returns ListOfShape from TopTools
+    is redefined;
+    ---C++: return const & 
+
 fields 
     myNbArgs    : Integer from Standard    is protected;
     myOperation : Operation from BOPAlgo   is protected; 
diff --git a/src/BOPAlgo/BOPAlgo_BOP_1.cxx b/src/BOPAlgo/BOPAlgo_BOP_1.cxx
index 6dd627f07e..6ce06ed151 100644
--- a/src/BOPAlgo/BOPAlgo_BOP_1.cxx
+++ b/src/BOPAlgo/BOPAlgo_BOP_1.cxx
@@ -136,3 +136,45 @@
   //
   myShape=aRC;
 }
+
+//=======================================================================
+//function : Generated
+//purpose  : 
+//=======================================================================
+const TopTools_ListOfShape& BOPAlgo_BOP::Generated(const TopoDS_Shape& theS)
+{
+  myHistShapes.Clear();
+  if (theS.IsNull() || (myOperation != BOPAlgo_SECTION)) {
+    return myHistShapes;
+  }
+  //
+  TopAbs_ShapeEnum aType = theS.ShapeType();
+  if (aType != TopAbs_FACE) {
+    return myHistShapes;
+  }
+  //
+  Standard_Integer nS = myDS->Index(theS);
+  if (nS < 0) {
+    return myHistShapes;
+  }
+  //
+  if (!myDS->HasFaceInfo(nS)) {
+    return myHistShapes;
+  }
+  //
+  //collect section edges of the face theS
+  Standard_Integer i, aNb, nSp;
+  //
+  const BOPDS_FaceInfo& aFI = myDS->FaceInfo(nS);
+  const BOPDS_IndexedMapOfPaveBlock& aMPBSc = aFI.PaveBlocksSc();
+  aNb = aMPBSc.Extent();
+  for (i = 1; i <= aNb; ++i) {
+    const Handle(BOPDS_PaveBlock)& aPB = aMPBSc(i);
+    nSp = aPB->Edge();
+    const TopoDS_Shape& aSp = myDS->Shape(nSp);
+    myHistShapes.Append(aSp);
+  }
+  //
+  return myHistShapes;
+}
+
diff --git a/src/BOPAlgo/BOPAlgo_Builder_4.cxx b/src/BOPAlgo/BOPAlgo_Builder_4.cxx
index f22482b300..ca706f2204 100644
--- a/src/BOPAlgo/BOPAlgo_Builder_4.cxx
+++ b/src/BOPAlgo/BOPAlgo_Builder_4.cxx
@@ -29,55 +29,9 @@
 //function : Generated
 //purpose  : 
 //=======================================================================
-  const TopTools_ListOfShape& BOPAlgo_Builder::Generated(const TopoDS_Shape& theS)
+  const TopTools_ListOfShape& BOPAlgo_Builder::Generated(const TopoDS_Shape&)
 {
-  Standard_Boolean bHasImage, bToReverse;
-  TopAbs_ShapeEnum aType;
-  BOPCol_ListIteratorOfListOfShape aIt;
-  //
   myHistShapes.Clear();
-  //
-  if (theS.IsNull()) {
-    return myHistShapes;
-  }
-  //
-  bHasImage=myImages.IsBound(theS);
-  if (!bHasImage) {
-    return myHistShapes;
-  }
-  //
-  aType=theS.ShapeType();
-  //
-  if (!(aType==TopAbs_EDGE   || aType==TopAbs_FACE || 
-      aType==TopAbs_VERTEX || aType==TopAbs_SOLID)) {
-    return myHistShapes;
-  } 
-  //
-  //PrepareHistory();
-  //
-  const BOPCol_ListOfShape& aLSp=myImages.Find(theS);
-  aIt.Initialize(aLSp);
-  for (; aIt.More(); aIt.Next()) {
-    const TopoDS_Shape& aSp=aIt.Value();
-    if (myShapesSD.IsBound(aSp)) {
-      if (myMapShape.Contains(aSp)) {
-	TopoDS_Shape aSpR=myShapesSD.Find(aSp);
-	//
-	if (aType==TopAbs_VERTEX || aType==TopAbs_SOLID) {
-	  aSpR.Orientation(theS.Orientation());
-	}
-	else {
-	  bToReverse=BOPTools_AlgoTools::IsSplitToReverse(aSpR, theS, myContext);
-	  if (bToReverse) {
-	    aSpR.Reverse();
-	  }
-	}
-	//
-	  myHistShapes.Append(aSpR);
-      }
-    }
-  }
-  //
   return myHistShapes;
 }
 //=======================================================================
@@ -114,21 +68,23 @@
   aIt.Initialize(aLSp);
   for (; aIt.More(); aIt.Next()) {
     TopoDS_Shape aSp=aIt.Value();
-    if (!myShapesSD.IsBound(aSp)) {
-      if (myMapShape.Contains(aSp)) {
-	//
-	if (aType==TopAbs_VERTEX || aType==TopAbs_SOLID) {
-	  aSp.Orientation(theS.Orientation());
-	}
-	else {
-	  bToReverse=BOPTools_AlgoTools::IsSplitToReverse(aSp, theS, myContext);
-	  if (bToReverse) {
-	    aSp.Reverse();
-	  }
-	}
-	//
-	myHistShapes.Append(aSp);
+    if (myShapesSD.IsBound(aSp)) {
+      aSp = myShapesSD.Find(aSp);
+    }
+    //
+    if (myMapShape.Contains(aSp)) {
+      //
+      if (aType==TopAbs_VERTEX || aType==TopAbs_SOLID) {
+        aSp.Orientation(theS.Orientation());
       }
+      else {
+        bToReverse=BOPTools_AlgoTools::IsSplitToReverse(aSp, theS, myContext);
+        if (bToReverse) {
+          aSp.Reverse();
+        }
+      }
+      //
+      myHistShapes.Append(aSp);
     }
   }
   //
@@ -175,13 +131,13 @@
     //
     if (!myShapesSD.IsBound(aSp)) {
       if (myMapShape.Contains(aSp)) {
-	return bRet; //false
+        return bRet; //false
       }
     }
     else {
       TopoDS_Shape aSpR=myShapesSD.Find(aSp);
       if (myMapShape.Contains(aSpR)) {
-	return bRet; //false
+        return bRet; //false
       }
     }
   }
@@ -201,7 +157,7 @@
     return;
   }
   //
-  Standard_Boolean bHasImage, bContainsSD;
+  Standard_Boolean bHasImage;
   TopAbs_ShapeEnum aType;
   BOPCol_MapOfShape aMS;
   BOPCol_ListIteratorOfListOfShape aIt;
@@ -232,18 +188,18 @@
     BOPCol_ListOfShape aLSx;
     if (!bHasImage) {
       if (myMapShape.Contains(aSx)) {
-	aLSx.Append(aSx);
-	myImagesResult.Add(aSx, aLSx);
+        aLSx.Append(aSx);
+        myImagesResult.Add(aSx, aLSx);
       }
     }
     else {
       const BOPCol_ListOfShape& aLSp=myImages.Find(aSx);
       aIt.Initialize(aLSp);
       for (; aIt.More(); aIt.Next()) {
-	const TopoDS_Shape& aSp=aIt.Value();
-	if (myMapShape.Contains(aSp)) {
-	  aLSx.Append(aSp);
-	}
+        const TopoDS_Shape& aSp=aIt.Value();
+        if (myMapShape.Contains(aSp)) {
+          aLSx.Append(aSp);
+        }
       }
       myImagesResult.Add(aSx, aLSx);
     }
@@ -254,55 +210,19 @@
       myHasDeleted=IsDeleted(aSx);
     }
     //
-    if (!myHasGenerated || !myHasModified) {
+    if (!myHasModified && bHasImage) {
       if (aType==TopAbs_EDGE   || aType==TopAbs_FACE || 
-	  aType==TopAbs_VERTEX || aType==TopAbs_SOLID) {
-	if (bHasImage) {
-	  const BOPCol_ListOfShape& aLSp=myImages.Find(aSx);
-	  aIt.Initialize(aLSp);
-	  for (; aIt.More(); aIt.Next()) {
-	    const TopoDS_Shape& aSp=aIt.Value();
-	    //
-	    if (myMapShape.Contains(aSp)) {
-	      bContainsSD=myShapesSD.IsBound(aSp);
-	      //
-	      if (!myHasGenerated) {
-		if (bContainsSD) {
-		  myHasGenerated=Standard_True;
-		}
-	      }
-	      if (!myHasModified) {
-		if (!bContainsSD) {
-		  myHasModified=Standard_True;
-		}
-	      }
-	    } // if (myMapShape.Contains(aSp))
-	  }
-	}
+          aType==TopAbs_VERTEX || aType==TopAbs_SOLID) {
+        myHasModified = Standard_True;
       } 
     }
+    //
+    if (!myHasGenerated) {
+      if (aType==TopAbs_FACE) {
+        const TopTools_ListOfShape& aLG = Generated(aSx);
+        myHasGenerated = aLG.Extent() > 0;
+      }
+    }
   }
   myFlagHistory=Standard_True;
 }
-
-// <- A
-    /*
-    BOPCol_ListOfShape aLSx;
-    if (!bHasImage) {
-      if (myMapShape.Contains(aSx)) {
-	aLSx.Append(aSx);
-	myImagesResult.Add(aSx, aLSx);
-      }
-    }
-    else {
-      const BOPCol_ListOfShape& aLSp=myImages.Find(aSx);
-      aIt.Initialize(aLSp);
-      for (; aIt.More(); aIt.Next()) {
-	const TopoDS_Shape& aSp=aIt.Value();
-	if (myMapShape.Contains(aSp)) {
-	  aLSx.Append(aSp);
-	}
-      }
-      myImagesResult.Add(aSx, aLSx);
-    }
-    */