diff --git a/EgtGeomKernel.rc b/EgtGeomKernel.rc
index eb41f30..bf01683 100644
Binary files a/EgtGeomKernel.rc and b/EgtGeomKernel.rc differ
diff --git a/GdbObj.cpp b/GdbObj.cpp
index ff3620d..87debbc 100644
--- a/GdbObj.cpp
+++ b/GdbObj.cpp
@@ -822,11 +822,19 @@ GdbObj::RemoveName( void)
 bool
 GdbObj::SetInfo( const string& sKey, const string& sInfo)
 {
-  // verifico esistenza (con eventuale creazione) degli attributi
-   if ( GetSafeAttribs() == nullptr)
-      return false ;
-  // assegno l'Info
-   return m_pAttribs->SetInfo( sKey, sInfo) ;
+  // se Info non vuota
+   if ( ! IsEmptyOrSpaces( sInfo)) {
+     // verifico esistenza (con eventuale creazione) degli attributi
+      if ( GetSafeAttribs() == nullptr)
+         return false ;
+     // eseguo assegnazione
+      return m_pAttribs->SetInfo( sKey, sInfo) ;
+   }
+  // altrimenti
+   else {
+     // se esiste, la rimuovo
+      return ( m_pAttribs == nullptr  ||  m_pAttribs->RemoveInfo( sKey)) ;
+   }
 }
 
 //----------------------------------------------------------------------------
diff --git a/Polygon3d.cpp b/Polygon3d.cpp
index 78b4188..40187f5 100644
--- a/Polygon3d.cpp
+++ b/Polygon3d.cpp
@@ -1,7 +1,7 @@
 //----------------------------------------------------------------------------
-//  EgalTech 2015-2017
+//  EgalTech 2015-2020
 //----------------------------------------------------------------------------
-// File : Polygon3d.cpp         Data : 15.10.17         Versione : 1.8j3
+// File : Polygon3d.cpp         Data : 03.04.20         Versione : 2.2d1
 // Contenuto : Implementazione della classe Polygon3d.
 //
 //
@@ -14,6 +14,9 @@
 //--------------------------- Include ----------------------------------------
 #include "stdafx.h"
 #include "PolygonPlane.h"
+#include "CurveComposite.h"
+#include "SurfFlatRegion.h"
+#include "GeoConst.h"
 #include "/EgtDev/Include/EgkPolygon3d.h"
 
 using namespace std ;
@@ -39,6 +42,8 @@ Polygon3d::ClearSides( void)
 bool
 Polygon3d::FromRectangle( double dDimX, double dDimY)
 {
+  // pulisco tutto
+   Clear() ;
   // verifico i dati
    if ( dDimX < EPS_SMALL  ||  dDimY < EPS_SMALL)
       return false ;
@@ -57,8 +62,8 @@ Polygon3d::FromRectangle( double dDimX, double dDimY)
 bool
 Polygon3d::FromTriangle( const Triangle3d& trTria)
 {
-  // annullo il piano del poligono
-   m_Plane.Reset() ;
+  // pulisco tutto
+   Clear() ;
   // verifico che il triangolo sia valido
    if ( ! trTria.IsValid())
       return false ;
@@ -76,8 +81,8 @@ Polygon3d::FromTriangle( const Triangle3d& trTria)
 bool
 Polygon3d::FromPolyLine( const PolyLine& PL)
 {
-  // annullo il piano del poligono
-   m_Plane.Reset() ;
+  // pulisco tutto
+   Clear() ;
   // verifico sia chiusa e piana
    Plane3d plPlane ;
    double dArea ;
@@ -101,6 +106,8 @@ Polygon3d::FromPolyLine( const PolyLine& PL)
 bool
 Polygon3d::FromPlaneTrimmedWithBox( const Plane3d& plPlane, const Point3d& ptMin, const Point3d& ptMax)
 {
+  // pulisco tutto
+   Clear() ;
   // il piano e il box devono essere validi
    if ( plPlane.GetVersN().IsSmall()  ||  AreSamePointApprox( ptMin, ptMax))
       return false ;
@@ -140,8 +147,7 @@ bool
 Polygon3d::FromPlaneTrimmedWithBox( const Point3d& ptOn, const Vector3d& vtN, const Point3d& ptMin, const Point3d& ptMax)
 {
    Plane3d plPlane ;
-   if ( plPlane.Set( ptOn, vtN))
-      return false ;
+   plPlane.Set( ptOn, vtN) ;
    return FromPlaneTrimmedWithBox( plPlane, ptMin, ptMax) ;
 }
 
@@ -236,6 +242,40 @@ Polygon3d::Trim( const Polygon3d& plyOther, bool bInVsOut, bool bOnEq)
    return Trim( plyOther.m_Plane, bInVsOut, bOnEq) ;
 }
 
+//----------------------------------------------------------------------------
+bool
+Polygon3d::Add( const Polygon3d& plyOther)
+{
+  // verifico non siano vuoti
+   if ( GetSideCount() == 0  ||  ! plyOther.IsValid())
+      return true ;
+  // verifico siano complanari
+   if ( ! AreSameVectorApprox( GetVersN(), plyOther.GetVersN())  &&
+        abs( GetPlaneDist() - plyOther.GetPlaneDist()) > EPS_SMALL)
+      return false ;
+  // creo la regione del poligono
+   CurveComposite crvThis ;
+   crvThis.FromPolyLine( GetPolyLine()) ;
+   SurfFlatRegion frThis ;
+   if ( ! frThis.AddExtLoop( crvThis))
+      return false ;
+  // creo la regione dell'altro poligono
+   CurveComposite crvOther ;
+   crvOther.FromPolyLine( plyOther.GetPolyLine()) ;
+   SurfFlatRegion frOther ;
+   if ( ! frOther.AddExtLoop( crvOther))
+      return false ;
+  // unisco le due regioni e verifico che il risultato sia un solo pezzo
+   if ( ! frThis.Add( frOther)  &&  frThis.GetChunkCount() != 1)
+      return false ;
+  // recupero il contorno della regione
+   PolyLine PL ;
+   if ( ! frThis.ApproxLoopWithLines( 0, 0, EPS_SMALL, ANG_TOL_MIN_DEG, ICurve::APL_STD, PL))
+      return false ;
+  // lo impongo come nuovo poligono
+   return FromPolyLine( PL) ;
+}
+
 //----------------------------------------------------------------------------
 PolyLine
 Polygon3d::GetPolyLine( void) const
diff --git a/SurfFlatRegion.cpp b/SurfFlatRegion.cpp
index ac822e4..ab96739 100644
--- a/SurfFlatRegion.cpp
+++ b/SurfFlatRegion.cpp
@@ -84,22 +84,29 @@ SurfFlatRegion::AddExtLoop( const ICurve& cCrv)
 bool
 SurfFlatRegion::AddExtLoop( ICurve* pCrv)
 {
+  // acquisisco la curva
+   PtrOwner<ICurve> pMyCrv( pCrv) ;
+   if ( IsNull( pMyCrv))
+      return false ;
+  // verifico sia chiusa
+   if ( ! pMyCrv->IsClosed())
+      return false ;
   // verifico sia piana e imposto estrusione come normale al piano
    double dArea ;
    Plane3d plPlane ;
-   if ( ! pCrv->GetArea( plPlane, dArea))
+   if ( ! pMyCrv->GetArea( plPlane, dArea))
       return false ;
-   pCrv->SetExtrusion( plPlane.GetVersN()) ;
-   pCrv->SetThickness( 0) ;
+   pMyCrv->SetExtrusion( plPlane.GetVersN()) ;
+   pMyCrv->SetThickness( 0) ;
   // rimuovo eventuali sovrapposizioni (calcolate nel suo piano)
    ICURVEPLIST CrvLst ;
-   if ( ! RemoveCurveOverlaps( pCrv, true, true, CrvLst))
+   if ( ! RemoveCurveOverlaps( Release( pMyCrv), true, true, CrvLst))
       return false ;
   // aggiungo le singole curve
    bool bOk = true ;
-   for ( auto& pCrv : CrvLst) {
+   for ( auto& pSingCrv : CrvLst) {
      // se curva composita
-      CurveComposite* pCrvCo = GetBasicCurveComposite( pCrv) ;
+      CurveComposite* pCrvCo = GetBasicCurveComposite( pSingCrv) ;
       if ( pCrvCo != nullptr) {
         // unisco eventuali tratti allineati
          pCrvCo->MergeCurves( LIN_TOL_MIN, ANG_TOL_STD_DEG) ;
@@ -107,7 +114,7 @@ SurfFlatRegion::AddExtLoop( ICurve* pCrv)
          RemoveCurveSpikes( pCrvCo) ;
       }
      // aggiungo il loop
-      if ( ! AddSimpleExtLoop( pCrv))
+      if ( ! AddSimpleExtLoop( pSingCrv))
          bOk = false ;
    }
    return bOk ;
@@ -230,22 +237,29 @@ SurfFlatRegion::AddIntLoop( const ICurve& cCrv)
 bool
 SurfFlatRegion::AddIntLoop( ICurve* pCrv)
 {
+  // acquisisco la curva
+   PtrOwner<ICurve> pMyCrv( pCrv) ;
+   if ( IsNull( pMyCrv))
+      return false ;
+  // verifico sia chiusa
+   if ( ! pMyCrv->IsClosed())
+      return false ;
   // verifico sia piana e imposto estrusione come normale al piano
    double dArea ;
    Plane3d plPlane ;
-   if ( ! pCrv->GetArea( plPlane, dArea))
+   if ( ! pMyCrv->GetArea( plPlane, dArea))
       return false ;
-   pCrv->SetExtrusion( plPlane.GetVersN()) ;
-   pCrv->SetThickness( 0) ;
+   pMyCrv->SetExtrusion( plPlane.GetVersN()) ;
+   pMyCrv->SetThickness( 0) ;
   // rimuovo eventuali sovrapposizioni (calcolate nel suo piano)
    ICURVEPLIST CrvLst ;
-   if ( ! RemoveCurveOverlaps( pCrv, true, true, CrvLst))
+   if ( ! RemoveCurveOverlaps( Release( pMyCrv), true, true, CrvLst))
       return false ;
   // aggiungo le singole curve
    bool bOk = true ;
-   for ( auto& pCrv : CrvLst) {
+   for ( auto& pSingCrv : CrvLst) {
      // se curva composita
-      CurveComposite* pCrvCo = GetBasicCurveComposite( pCrv) ;
+      CurveComposite* pCrvCo = GetBasicCurveComposite( pSingCrv) ;
       if ( pCrvCo != nullptr) {
         // unisco eventuali tratti allineati
          pCrvCo->MergeCurves( LIN_TOL_MIN, ANG_TOL_STD_DEG) ;
@@ -253,7 +267,7 @@ SurfFlatRegion::AddIntLoop( ICurve* pCrv)
          RemoveCurveSpikes( pCrvCo) ;
       }
      // aggiungo il loop
-      if ( ! AddSimpleIntLoop( pCrv))
+      if ( ! AddSimpleIntLoop( pSingCrv))
          bOk = false ;
    }
    return bOk ;
diff --git a/SurfTriMesh.h b/SurfTriMesh.h
index 9c4d6f5..ccff9df 100644
--- a/SurfTriMesh.h
+++ b/SurfTriMesh.h
@@ -156,13 +156,13 @@ class SurfTriMesh : public ISurfTriMesh, public IGeoObjRW
       bool CopyFrom( const IGeoObj* pGObjSrc) override ;
       bool Init( int nNumVert, int nNumTria, int nNumFacet = 0) override ;
       void SetLinearTolerance( double dLinTol) override
-              { m_dLinTol = (std::max)( dLinTol, EPS_SMALL) ; }
+              { m_dLinTol = std::max( dLinTol, EPS_SMALL) ; }
       void SetBoundaryAngle( double dBoundaryAngDeg) override
-              { m_dBoundaryAng = (std::max)( dBoundaryAngDeg, EPS_ANG_SMALL) ;
+              { m_dBoundaryAng = std::max( dBoundaryAngDeg, EPS_ANG_SMALL) ;
                 m_dCosBndAng = cos( m_dBoundaryAng * DEGTORAD) ;
                 m_OGrMgr.Reset() ; }
       void SetSmoothAngle( double dSmoothAngDeg) override
-              { m_dSmoothAng = (std::max)( dSmoothAngDeg, EPS_ANG_SMALL) ;
+              { m_dSmoothAng = std::max( dSmoothAngDeg, EPS_ANG_SMALL) ;
                 m_dCosSmAng = cos( m_dSmoothAng * DEGTORAD) ;
                 m_OGrMgr.Reset() ; }
       int  AddVertex( const Point3d& ptVert) override ;