diff --git a/EGkCurve.h b/EGkCurve.h
index d1f815e..9c47580 100644
--- a/EGkCurve.h
+++ b/EGkCurve.h
@@ -41,7 +41,7 @@ class __declspec( novtable) ICurve : public IGeoObj
                      OFF_FORCE_OPEN = 8,    // forza a aperto anche se chiuso (in or ...)
                      OFF_NO_VERTICAL = 16} ;// vieta linee perpendicolari al piano di offset (in or ...)
    public :                      // IGeoObj
-      virtual ICurve* Clone( void) const = 0 ;
+      ICurve* Clone( void) const override = 0 ;
    public :
       virtual bool IsSimple( void) const = 0 ;
       virtual bool IsClosed( void) const = 0 ;
diff --git a/EGkCurveArc.h b/EGkCurveArc.h
index 4dffcbe..6e7d4fc 100644
--- a/EGkCurveArc.h
+++ b/EGkCurveArc.h
@@ -18,6 +18,8 @@
 //----------------------------------------------------------------------------
 class __declspec( novtable) ICurveArc : public ICurve
 {
+   public :                      // IGeoObj
+      ICurveArc* Clone( void) const override = 0 ;
    public :
       virtual bool CopyFrom( const IGeoObj* pGObjSrc) = 0 ;
       virtual bool Set( const Point3d& ptCen, const Vector3d& vtN, double dRad,
diff --git a/EGkCurveBezier.h b/EGkCurveBezier.h
index b7438cd..8231cba 100644
--- a/EGkCurveBezier.h
+++ b/EGkCurveBezier.h
@@ -20,6 +20,8 @@ class ICurveArc ;
 //----------------------------------------------------------------------------
 class __declspec( novtable) ICurveBezier : public ICurve
 {
+   public :                      // IGeoObj
+      ICurveBezier* Clone( void) const override = 0 ;
    public :
       virtual bool CopyFrom( const IGeoObj* pGObjSrc) = 0 ;
       virtual bool Init( int nDeg, bool bIsRational) = 0 ;
diff --git a/EGkCurveComposite.h b/EGkCurveComposite.h
index fcea436..30a0e93 100644
--- a/EGkCurveComposite.h
+++ b/EGkCurveComposite.h
@@ -18,6 +18,8 @@
 //----------------------------------------------------------------------------
 class __declspec( novtable) ICurveComposite : public ICurve
 {
+   public :                      // IGeoObj
+      ICurveComposite* Clone( void) const override = 0 ;
    public :
       virtual bool CopyFrom( const IGeoObj* pGObjSrc) = 0 ;
       virtual bool Clear( void) = 0 ;
diff --git a/EGkCurveLine.h b/EGkCurveLine.h
index 5b7feec..e2b3388 100644
--- a/EGkCurveLine.h
+++ b/EGkCurveLine.h
@@ -18,6 +18,8 @@
 //----------------------------------------------------------------------------
 class __declspec( novtable) ICurveLine : public ICurve
 {
+   public :                      // IGeoObj
+      ICurveLine* Clone( void) const override = 0 ;
    public :
       virtual bool CopyFrom( const IGeoObj* pGObjSrc) = 0 ;
       virtual bool Set( const Point3d& ptStart, const Point3d& ptEnd) = 0 ;
diff --git a/EGkPlane3d.h b/EGkPlane3d.h
index 195c222..363c89d 100644
--- a/EGkPlane3d.h
+++ b/EGkPlane3d.h
@@ -87,6 +87,13 @@ SetPlane( const Point3d& ptP, const Vector3d& vtN, Plane3d& plPlane)
    return true ;
 }
 
+//-----------------------------------------------------------------------------
+inline double
+DistPointPlane( const Point3d& ptP, const Plane3d& plPlane)
+{
+   return ((( ptP - ORIG) * plPlane.vtN) - plPlane.dDist) ;
+}
+
 //-----------------------------------------------------------------------------
 inline bool
 PointInPlaneApprox( const Point3d& ptP, const Plane3d& plPlane)
diff --git a/EGkSurf.h b/EGkSurf.h
index eee7c55..346d9bc 100644
--- a/EGkSurf.h
+++ b/EGkSurf.h
@@ -18,6 +18,8 @@
 //----------------------------------------------------------------------------
 class __declspec( novtable) ISurf : public IGeoObj
 {
+   public :                      // IGeoObj
+      ISurf* Clone( void) const override = 0 ;
    public :
       virtual bool IsSimple( void) const = 0 ;
       virtual bool IsClosed( void) const = 0 ;
diff --git a/EGkSurfFlatRegion.h b/EGkSurfFlatRegion.h
index d693544..16270b3 100644
--- a/EGkSurfFlatRegion.h
+++ b/EGkSurfFlatRegion.h
@@ -21,6 +21,8 @@ class ISurfTriMesh ;
 //----------------------------------------------------------------------------
 class __declspec( novtable) ISurfFlatRegion : public ISurf
 {
+   public :                      // IGeoObj
+      ISurfFlatRegion* Clone( void) const override = 0 ;
    public :
       virtual bool CopyFrom( const IGeoObj* pGObjSrc) = 0 ;
       virtual bool Clear( void) ;
diff --git a/EGkSurfTriMesh.h b/EGkSurfTriMesh.h
index 8fdbe3d..e71cba3 100644
--- a/EGkSurfTriMesh.h
+++ b/EGkSurfTriMesh.h
@@ -20,10 +20,14 @@
 //----------------------------------------------------------------------------
 const int SVT_NULL = - 1 ;           // vertice o triangolo nullo
 const int SVT_DEL = - 2 ;            // vertice o triangolo cancellato
+inline bool IsValidSvt( int nSvt)
+               { return ( nSvt != SVT_NULL  &&  nSvt != SVT_DEL) ; }
 
 //----------------------------------------------------------------------------
 class __declspec( novtable) ISurfTriMesh : public ISurf
 {
+   public :                      // IGeoObj
+      ISurfTriMesh* Clone( void) const override = 0 ;
    public :
       virtual bool CopyFrom( const IGeoObj* pGObjSrc) = 0 ;
       virtual bool Init( int nNumVert, int nNumTria, int nNumFacet = 0) = 0 ;
@@ -77,6 +81,7 @@ class __declspec( novtable) ISurfTriMesh : public ISurf
       virtual bool GetFacetNormal( int nF, Vector3d& vtN) const = 0 ;
       virtual bool GetFacetArea( int nF, double& dArea) const = 0 ;
       virtual ISurfTriMesh* CloneFacet( int nF) const = 0 ;
+      virtual bool Cut( const Plane3d& plPlane, bool bSaveOnEq) = 0 ;
 } ;
 
 //-----------------------------------------------------------------------------
diff --git a/EXeExecutor.h b/EXeExecutor.h
index ade99a3..487cd2c 100644
--- a/EXeExecutor.h
+++ b/EXeExecutor.h
@@ -458,6 +458,7 @@ EXE_EXPORT int  ExeExtractSurfTmLoops( int nId, int nDestGrpId, int* pnCount) ;
 EXE_EXPORT int  ExeGetSurfTmSilhouette( int nId, const Vector3d& vtDir, int nDestGrpId, int nRefType, int* pnCount) ;
 EXE_EXPORT int  ExeExtractSurfTmFacetLoops( int nId, int nFacet, int nDestGrpId, int* pnCount) ;
 EXE_EXPORT int  ExeCopySurfTmFacet( int nId, int nFacet, int nDestGrpId) ;
+EXE_EXPORT bool ExeCutSurfTm( int nId, const Point3d& ptOn, const Vector3d& vtN, bool bSaveOnEq, int nRefType) ;
 
 // GeomDb Volume Modify
 EXE_EXPORT bool ExeVolZmapSetStdTool( int nId, const std::string& sToolName, double dLen, double dDiam, double dCornR) ;