diff --git a/CurveComposite.cpp b/CurveComposite.cpp
index 3e87ed3..29875b5 100644
--- a/CurveComposite.cpp
+++ b/CurveComposite.cpp
@@ -1096,24 +1096,6 @@ CurveComposite::GetPointD1D2( double dU, Side nS, Point3d& ptPos, Vector3d* pvtD
    return m_CrvSmplS[nC]->GetPointD1D2( dUc, ICurve::FROM_MINUS, ptPos, pvtDer1, pvtDer2) ;
 }
 
-//----------------------------------------------------------------------------
-bool
-CurveComposite::IsAPoint( void) const
-{
-  // verifico lo stato
-   if ( m_nStatus != OK)
-      return false ;
-
-  // ciclo di verifica
-   for ( auto Iter = m_CrvSmplS.begin() ; Iter != m_CrvSmplS.end() ; ++Iter) {
-      if ( (*Iter)->GetType() != CRV_BEZIER  ||
-           ! GetBasicCurveBezier(*Iter)->IsAPoint())
-         return false ;
-   }
-
-   return true ;
-}
-
 //----------------------------------------------------------------------------
 bool
 CurveComposite::GetApproxLength( double& dLen) const
@@ -1838,6 +1820,75 @@ CurveComposite::RemoveJoint( int nU)
    return true ;                                               
 }
 
+//----------------------------------------------------------------------------
+bool
+CurveComposite::ModifyCurveToArc( int nCrv, const Point3d& ptMid)
+{
+  // verifico lo stato
+   if ( m_nStatus != OK)
+      return false ;
+  // numero di curve
+   int nCrvCount = GetCurveCount() ;
+  // la curva deve esistere
+   if ( nCrv < 0  ||  nCrv > nCrvCount - 1)
+      return false ;
+  // recupero la curva corrente 
+   ICurve* pCrv = *(m_CrvSmplS.begin() + nCrv) ;
+  // recupero gli estremi
+   Point3d ptStart, ptEnd ;
+   if ( ! pCrv->GetStartPoint( ptStart)  ||  ! pCrv->GetEndPoint( ptEnd))
+      return false ;
+  // creo l'arco
+   PtrOwner<CurveArc> pArc( CreateBasicCurveArc()) ;
+   if ( IsNull( pArc)  ||  ! pArc->Set3P( ptStart, ptMid, ptEnd))
+      return false ;
+  // sostituisco l'arco alla curva precedente
+   m_CrvSmplS[nCrv] = Release( pArc) ;
+  // elimino la curva originale
+   delete( pCrv) ;
+
+  // imposto ricalcolo della grafica
+   m_OGrMgr.Reset() ;
+
+   return true ;                                               
+}
+
+//----------------------------------------------------------------------------
+bool
+CurveComposite::ModifyCurveToLine( int nCrv)
+{
+  // verifico lo stato
+   if ( m_nStatus != OK)
+      return false ;
+  // numero di curve
+   int nCrvCount = GetCurveCount() ;
+  // la curva deve esistere
+   if ( nCrv < 0  ||  nCrv > nCrvCount - 1)
+      return false ;
+  // recupero la curva corrente 
+   ICurve* pCrv = *(m_CrvSmplS.begin() + nCrv) ;
+  // se giā linea non devo fare alcunchč
+   if ( pCrv->GetType() == CRV_LINE)
+      return true ;
+  // recupero gli estremi
+   Point3d ptStart, ptEnd ;
+   if ( ! pCrv->GetStartPoint( ptStart)  ||  ! pCrv->GetEndPoint( ptEnd))
+      return false ;
+  // creo la linea
+   PtrOwner<CurveLine> pLine( CreateBasicCurveLine()) ;
+   if ( IsNull( pLine)  ||  ! pLine->Set( ptStart, ptEnd))
+      return false ;
+  // sostituisco la linea alla curva precedente
+   m_CrvSmplS[nCrv] = Release( pLine) ;
+  // elimino la curva originale
+   delete( pCrv) ;
+
+  // imposto ricalcolo della grafica
+   m_OGrMgr.Reset() ;
+
+   return true ;                                               
+}
+
 //----------------------------------------------------------------------------
 bool
 CurveComposite::TrimStartAtParam( double dUTrim)
@@ -2963,6 +3014,52 @@ CurveComposite::RemoveUndercutOnY( double dLinTol, double dAngTolDeg)
    return AddCurve( Release( pOutLoop)) ;
 }
 
+//----------------------------------------------------------------------------
+bool
+CurveComposite::IsAPoint( void) const
+{
+  // verifico lo stato
+   if ( m_nStatus != OK)
+      return false ;
+
+  // ciclo di verifica
+   for ( auto Iter = m_CrvSmplS.begin() ; Iter != m_CrvSmplS.end() ; ++Iter) {
+      if ( (*Iter)->GetType() != CRV_BEZIER  ||
+           ! GetBasicCurveBezier(*Iter)->IsAPoint())
+         return false ;
+   }
+
+   return true ;
+}
+
+//----------------------------------------------------------------------------
+bool
+CurveComposite::IsALine( double dLinTol, Point3d& ptStart, Point3d& ptEnd) const
+{
+  // verifico lo stato
+   if ( m_nStatus != OK  ||  m_CrvSmplS.empty())
+      return false ;
+
+  // recupero gli estremi
+   if ( ! m_CrvSmplS.front()->GetStartPoint( ptStart)  ||
+        ! m_CrvSmplS.back()->GetEndPoint( ptEnd))
+      return false ;
+
+  // verifico non siano coincidenti
+   if ( AreSamePointEpsilon( ptStart, ptEnd, min( dLinTol, EPS_SMALL)))
+      return false ;
+
+  // provo ad approssimarla con segmenti e verifico se si riduce ad un segmento di retta
+   PolyLine PL ;
+   if ( ! ApproxWithLines( dLinTol, ANG_TOL_STD_DEG, APL_SPECIAL, PL))
+      return false ;
+  // elimino i punti allineati entro la tolleranza
+   if ( ! PL.RemoveAlignedPoints( dLinTol))
+      return false ;
+  // se sono rimasti due punti č una retta
+   return ( PL.GetPointNbr() == 2) ;
+}
+
 //----------------------------------------------------------------------------
 bool
 CurveComposite::IsOneCircle( Point3d& ptCen, Vector3d& vtN, double& dRad, bool& bCCW) const
diff --git a/CurveComposite.h b/CurveComposite.h
index 9cc7acb..9b4fc0e 100644
--- a/CurveComposite.h
+++ b/CurveComposite.h
@@ -1,7 +1,7 @@
 //----------------------------------------------------------------------------
-//  EgalTech 2013-2013
+//  EgalTech 2013-2021
 //----------------------------------------------------------------------------
-// File : CurveComposite.h       Data : 23.11.13          Versione : 1.3a1
+// File : CurveComposite.h       Data : 03.04.21          Versione : 2.3d1
 // Contenuto : Dichiarazione della classe Curva composita.
 //
 //
@@ -148,11 +148,14 @@ class CurveComposite : public ICurveComposite, public IGeoObjRW
       bool AddJoint( double dU) override ;
       bool ModifyJoint( int nU, const Point3d& ptNewJoint) override ;
       bool RemoveJoint( int nU) override ;
+      bool ModifyCurveToArc( int nCrv, const Point3d& ptMid) override ;
+      bool ModifyCurveToLine( int nCrv) override ;
       bool ArcsToBezierCurves( void) override ;
       bool ArcsBezierCurvesToArcsPerpExtr( double dLinTol, double dAngTolDeg) override ;
       bool MergeCurves( double dLinTol, double dAngTolDeg, bool bStartEnd = true, bool bNeedSameProp = false) override ;
       bool RemoveUndercutOnY( double dLinTol, double dAngTolDeg) override ;
       bool IsAPoint( void) const override ;
+      bool IsALine( double dLinTol, Point3d& ptStart, Point3d& ptEnd) const override ;
       bool IsACircle( double dLinTol, Point3d& ptCen, Vector3d& vtN, double& dRad, bool& bCCW) const override ;
       bool SetCurveTempProp( int nCrv, int nProp) override ;
       bool GetCurveTempProp( int nCrv, int& nProp) const override ;