diff --git a/EGkPolyArc.h b/EGkPolyArc.h
new file mode 100644
index 0000000..377f555
--- /dev/null
+++ b/EGkPolyArc.h
@@ -0,0 +1,72 @@
+//----------------------------------------------------------------------------
+//  EgalTech 2014-2014
+//----------------------------------------------------------------------------
+// File : EGkPolyArc.h         Data : 14.08.14          Versione : 1.5h3
+// Contenuto : Dichiarazione della classe PolyArc.
+//
+//
+//
+// Modifiche : 14.08.14 DS Creazione modulo.
+//
+//
+//----------------------------------------------------------------------------
+
+#pragma once
+
+#include "/EgtDev/Include/EGkPoint3d.h"
+#include "/EgtDev/Include/EGkGeoCollection.h"
+
+class Plane3d ;
+
+//----------------------- Macro per import/export ----------------------------
+#undef EGK_EXPORT
+#if defined( I_AM_EGK)            // da definirsi solo nella DLL
+   #define EGK_EXPORT __declspec( dllexport)
+#else
+   #define EGK_EXPORT __declspec( dllimport)
+#endif
+
+//-----------------------------------------------------------------------------
+class PolyArc
+{
+   public :
+      EGK_EXPORT PolyArc( void) ;
+      EGK_EXPORT ~PolyArc( void) ;
+      EGK_EXPORT bool Clear( void) ;
+      EGK_EXPORT bool AddUPoint( double dPar, const Point3d& ptP, double dBulge) ;
+      EGK_EXPORT bool EraseFirstUPoint( void) ;
+      EGK_EXPORT bool EraseLastUPoint( void) ;
+      EGK_EXPORT bool AddOffsetToU( double dOffset) ;
+      EGK_EXPORT bool ToGlob( const Frame3d& frRef) ;
+      EGK_EXPORT bool ToLoc( const Frame3d& frRef) ;
+      EGK_EXPORT bool LocToLoc( const Frame3d& frOri, const Frame3d& frDest) ;
+      EGK_EXPORT bool Splice( PolyArc& PA) ;
+      EGK_EXPORT int  GetPointNbr( void) const
+                        { return m_nCount ; }
+      EGK_EXPORT bool GetFirstUPoint( double* pdPar, Point3d* pptP, double* pdBulge) const ;
+      EGK_EXPORT bool GetNextUPoint( double* pdPar, Point3d* pptP, double* pdBulge, bool bNotLast = false) const ;
+      EGK_EXPORT bool GetFirstU( double& dPar) const
+                        { return GetFirstUPoint( &dPar, nullptr, nullptr) ; }
+      EGK_EXPORT bool GetNextU( double& dPar, bool bNotLast = false) const
+                        { return GetNextUPoint( &dPar, nullptr, nullptr, bNotLast) ; }
+      EGK_EXPORT bool GetFirstPoint( Point3d& ptP, double& dBulge) const
+                        { return GetFirstUPoint( nullptr, &ptP, &dBulge) ; }
+      EGK_EXPORT bool GetNextPoint( Point3d& ptP, double& dBulge, bool bNotLast = false) const
+                        { return GetNextUPoint( nullptr, &ptP, &dBulge, bNotLast) ; }
+
+   private :
+      struct UPointB  
+      {
+         double  dU ;
+         Point3d ptP ;
+         double  dB ;
+         UPointB( double dU_, const Point3d& ptP_, double dB_)
+            : dU( dU_), ptP( ptP_), dB( dB_) {}
+      } ;
+      typedef std::list<UPointB>  UPNTBLIST ;   // lista di UPointB
+
+   private :
+      int       m_nCount ;
+      UPNTBLIST m_lUPointBs ;
+      mutable UPNTBLIST::const_iterator m_iter ;
+} ;
diff --git a/EGkPolyLine.h b/EGkPolyLine.h
index 65bdb31..efe1b47 100644
--- a/EGkPolyLine.h
+++ b/EGkPolyLine.h
@@ -86,16 +86,14 @@ class PolyLine
                         { return GetLastULine( nullptr, &ptIni, nullptr, &ptFin) ; }
       EGK_EXPORT bool GetPrevLine( Point3d& ptIni, Point3d& ptFin) const
                         { return GetPrevULine( nullptr, &ptIni, nullptr, &ptFin) ; }
-      EGK_EXPORT bool IsFlat( Plane3d& plPlane, double& dArea, double dToler = EPS_SMALL) const ;
+      EGK_EXPORT bool IsFlat( int& nRank, Point3d& ptCen, Vector3d& vtDir, double dToler = EPS_SMALL) const ;
+      EGK_EXPORT bool IsClosedAndFlat( Plane3d& plPlane, double& dArea, double dToler = EPS_SMALL) const ;
       EGK_EXPORT bool GetApproxLength( double& dLen) const ;
       EGK_EXPORT bool GetLength( double& dLen) const ;
       EGK_EXPORT bool GetAreaXY( double& dArea) const ;
       EGK_EXPORT bool GetMaxDistanceFromLine( double& dMaxDist, const Point3d& ptAx,
                                            const Vector3d& vtAx, double dLen, bool bIsSegment = true) const ;
 
-   private :
-      bool NewellPlane( Plane3d& plPlane, double& dArea) const ;
-
    private :
       int      m_nCount ;
       UPNTLIST m_lUPoints ;
diff --git a/EGkVector3d.h b/EGkVector3d.h
index b20797a..ae4f46f 100644
--- a/EGkVector3d.h
+++ b/EGkVector3d.h
@@ -38,16 +38,12 @@ class EGK_EXPORT Vector3d
       //! Costruttore del vettore nullo X = Y = Z = 0
       Vector3d( void) : x( 0), y( 0), z( 0) {}
       //! Assegnazione delle componenti X, Y e Z al vettore
-      void Set( double dX, double dY, double dZ) { x = dX ; y = dY ; z = dZ ;}
+      void Set( double dX, double dY, double dZ) { x = dX ; y = dY ; z = dZ ; }
       //! Copia
       const Vector3d& operator =( const Vector3d& vtSrc)
                          { if ( &vtSrc != this) {
                               x = vtSrc.x , y = vtSrc.y , z = vtSrc.z ; }
                            return *this ; }
-      //! Definizione a partire da coordinate sferiche
-      void FromSpherical( double dLen, double dAngVertDeg, double dAngOrizzDeg) ;
-      //! Definizione a partire da coordinate polari
-      void FromPolar( double dLen, double dAngDeg) ;
 
    public :
       //! Quadrato della lunghezza del vettore
@@ -101,7 +97,10 @@ class EGK_EXPORT Vector3d
              { double dMul = 1 / dDiv ; this->x *= dMul ; this->y *= dMul ; this->z *= dMul ; return *this ; }
       //! Ritorna la rappresentazione in coordinate sferiche
       void ToSpherical( double* pdLen, double* pdAngVertDeg, double* pdAngOrizzDeg) const ;
-      //! Normalizzazione di un vettore (trasformazione in versore)
+      //! Inversione del vettore
+      void Invert( void)
+             { x = - x ; y = - y ; z = - z ; }
+      //! Normalizzazione del vettore (trasformazione in versore)
       bool Normalize( double dEps = EPS_SMALL) ;
       //! Rotazione attorno ad un asse, dato l'angolo in gradi
       bool Rotate( const Vector3d& vtAx, double dAngDeg) ;
@@ -150,6 +149,21 @@ const Vector3d Y_AX( 0, 1, 0) ;
 //! Versore asse Z
 const Vector3d Z_AX( 0, 0, 1) ;
 
+//----------------------------------------------------------------------------
+//! Definizione a partire da coordinate sferiche
+//----------------------------------------------------------------------------
+EGK_EXPORT Vector3d FromSpherical( double dLen, double dAngVertDeg, double dAngOrizzDeg) ;
+
+//----------------------------------------------------------------------------
+//! Definizione a partire da coordinate polari ( nel piano XY, Z = 0)
+//----------------------------------------------------------------------------
+EGK_EXPORT Vector3d FromPolar( double dLen, double dAngDeg) ;
+
+//----------------------------------------------------------------------------
+//! Definizione come pił verticale dei vettori ortogonali a quello ricevuto
+//----------------------------------------------------------------------------
+EGK_EXPORT Vector3d FromUprightOrtho( const Vector3d& vtV) ;
+
 //----------------------------------------------------------------------------
 //! Opposto di un vettore
 //----------------------------------------------------------------------------
diff --git a/EgkCurve.h b/EgkCurve.h
index 62488af..2f64ca6 100644
--- a/EgkCurve.h
+++ b/EgkCurve.h
@@ -15,6 +15,8 @@
 
 #include "/EgtDev/Include/EGkGeoObj.h"
 #include "/EgtDev/Include/EGkPolyLine.h"
+#include "/EgtDev/Include/EGkPolyArc.h"
+#include "/EgtDev/Include/EGkPlane3d.h"
 
 //----------------------------------------------------------------------------
 class __declspec( novtable) ICurve : public IGeoObj
@@ -36,6 +38,7 @@ class __declspec( novtable) ICurve : public IGeoObj
    public :
       virtual bool IsSimple( void) const = 0 ;
       virtual bool IsClosed( void) const = 0 ;
+      virtual bool IsFlat( Plane3d& plPlane, double dToler = EPS_SMALL) const = 0 ;
       virtual bool GetStartPoint( Point3d& ptStart) const = 0 ;
       virtual bool GetEndPoint( Point3d& ptEnd) const = 0 ;
       virtual bool GetMidPoint( Point3d& ptMid) const = 0 ;
@@ -56,6 +59,7 @@ class __declspec( novtable) ICurve : public IGeoObj
       virtual bool GetPointDiffGeom( double dU, Side nS, CrvPointDiffGeom& oDiffG) const = 0 ;
       virtual bool IsPointOn( const Point3d& ptP, double dTol = EPS_SMALL) const = 0 ;
       virtual bool ApproxWithLines( double dLinTol, double dAngTolDeg, PolyLine& PL) const = 0 ;
+      virtual bool ApproxWithArcs( double dLinTol, double dAngTolDeg, PolyArc& PA) const = 0 ;
       virtual ICurve* CopyParamRange( double dUStart, double dUEnd) const = 0 ;
       virtual bool Invert( void) = 0 ;
       virtual bool Offset( double dDist, int nSide, int nType = OFF_FILLET) = 0 ;
diff --git a/EgkCurveArc.h b/EgkCurveArc.h
index 57ff74e..dbfe37a 100644
--- a/EgkCurveArc.h
+++ b/EgkCurveArc.h
@@ -30,7 +30,7 @@ class __declspec( novtable) ICurveArc : public ICurve
       virtual bool Set2PD( const Point3d& ptStart, const Point3d& ptEnd, double dDirStartDeg) = 0 ;
       virtual bool Set2PRS( const Point3d& ptStart, const Point3d& ptEnd, double dRad, bool bCCW = true) = 0 ;
       virtual bool SetC2P( const Point3d& ptCen, const Point3d& ptStart, const Point3d& ptNearEnd) = 0 ;
-      virtual bool IsFlat( void) const = 0 ;
+      virtual bool IsFlat( double dToler = EPS_SMALL) const = 0 ;
       virtual bool IsACircle( void) const = 0 ;
       virtual bool IsInPlaneXY( void) const = 0 ;
       virtual const Point3d& GetCenter( void) const = 0 ;