diff --git a/EXE_GdbModifySurf.cpp b/EXE_GdbModifySurf.cpp
index 080e743..c5c1a16 100644
--- a/EXE_GdbModifySurf.cpp
+++ b/EXE_GdbModifySurf.cpp
@@ -163,6 +163,123 @@ ExeExplodeSurface( int nId, int* pnCount)
    return nFirstId ;
 }
 
+//----------------------------------------------------------------------------
+bool
+ExeSurfFrAdd( int nId1, int nId2)
+{
+   IGeomDB* pGeomDB = GetCurrGeomDB() ;
+   VERIFY_GEOMDB( pGeomDB, GDB_ID_NULL)
+  // recupero la prima superficie FlatRegion
+   ISurfFlatRegion* pSfr1 = GetSurfFlatRegion( pGeomDB->GetGeoObj( nId1)) ;
+   bool bOk = ( pSfr1 != nullptr) ;
+  // recupero il riferimento della superficie
+   Frame3d frSurf1 ;
+   bOk = bOk && pGeomDB->GetGlobFrame( nId1, frSurf1) ;
+  // recupero la seconda superficie FlatRegion
+   const ISurfFlatRegion* pSfr2 = GetSurfFlatRegion( pGeomDB->GetGeoObj( nId2)) ;
+   bOk = bOk && ( pSfr2 != nullptr) ;
+  // recupero il riferimento della superficie
+   Frame3d frSurf2 ;
+   bOk = bOk && pGeomDB->GetGlobFrame( nId2, frSurf2) ;
+  // se riferimenti diversi, porto una copia della seconda nel riferimento della prima
+   const ISurfFlatRegion* pSfr2L = pSfr2 ;
+   PtrOwner<ISurfFlatRegion>pTmp ;
+   if ( ! AreSameFrame( frSurf1, frSurf2)) {
+      pTmp.Set( CloneSurfFlatRegion( pSfr2)) ;
+      bOk = bOk && ! IsNull( pTmp) ;
+      pSfr2L = Get( pTmp) ;
+   }
+  // eseguo l'unione tra le due superfici
+   bOk = bOk && pSfr1->Add( *pSfr2L) ;
+   ExeSetModified() ;
+  // se richiesto, salvo il comando Lua equivalente
+   if ( IsCmdLog()) {
+      string sLua = "EgtSurfFrAdd(" + ToString( nId1) + "," +
+                                      ToString( nId2) + ")" +
+                    " -- Ok=" + ToString( bOk) ;
+      LOG_INFO( GetCmdLogger(), sLua.c_str()) ;
+   }
+   return bOk ;
+}
+
+//----------------------------------------------------------------------------
+bool
+ExeSurfFrSubtract( int nId1, int nId2)
+{
+   IGeomDB* pGeomDB = GetCurrGeomDB() ;
+   VERIFY_GEOMDB( pGeomDB, GDB_ID_NULL)
+  // recupero la prima superficie FlatRegion
+   ISurfFlatRegion* pSfr1 = GetSurfFlatRegion( pGeomDB->GetGeoObj( nId1)) ;
+   bool bOk = ( pSfr1 != nullptr) ;
+  // recupero il riferimento della superficie
+   Frame3d frSurf1 ;
+   bOk = bOk && pGeomDB->GetGlobFrame( nId1, frSurf1) ;
+  // recupero la seconda superficie FlatRegion
+   const ISurfFlatRegion* pSfr2 = GetSurfFlatRegion( pGeomDB->GetGeoObj( nId2)) ;
+   bOk = bOk && ( pSfr2 != nullptr) ;
+  // recupero il riferimento della superficie
+   Frame3d frSurf2 ;
+   bOk = bOk && pGeomDB->GetGlobFrame( nId2, frSurf2) ;
+  // se riferimenti diversi, porto una copia della seconda nel riferimento della prima
+   const ISurfFlatRegion* pSfr2L = pSfr2 ;
+   PtrOwner<ISurfFlatRegion>pTmp ;
+   if ( ! AreSameFrame( frSurf1, frSurf2)) {
+      pTmp.Set( CloneSurfFlatRegion( pSfr2)) ;
+      bOk = bOk && ! IsNull( pTmp) ;
+      pSfr2L = Get( pTmp) ;
+   }
+  // eseguo la sottrazione della seconda superficie dalla prima
+   bOk = bOk && pSfr1->Subtract( *pSfr2L) ;
+   ExeSetModified() ;
+  // se richiesto, salvo il comando Lua equivalente
+   if ( IsCmdLog()) {
+      string sLua = "EgtSurfFrSubtract(" + ToString( nId1) + "," +
+                                           ToString( nId2) + ")" +
+                    " -- Ok=" + ToString( bOk) ;
+      LOG_INFO( GetCmdLogger(), sLua.c_str()) ;
+   }
+   return bOk ;
+}
+
+//----------------------------------------------------------------------------
+bool
+ExeSurfFrIntersect( int nId1, int nId2)
+{
+   IGeomDB* pGeomDB = GetCurrGeomDB() ;
+   VERIFY_GEOMDB( pGeomDB, GDB_ID_NULL)
+  // recupero la prima superficie FlatRegion
+   ISurfFlatRegion* pSfr1 = GetSurfFlatRegion( pGeomDB->GetGeoObj( nId1)) ;
+   bool bOk = ( pSfr1 != nullptr) ;
+  // recupero il riferimento della superficie
+   Frame3d frSurf1 ;
+   bOk = bOk && pGeomDB->GetGlobFrame( nId1, frSurf1) ;
+  // recupero la seconda superficie FlatRegion
+   const ISurfFlatRegion* pSfr2 = GetSurfFlatRegion( pGeomDB->GetGeoObj( nId2)) ;
+   bOk = bOk && ( pSfr2 != nullptr) ;
+  // recupero il riferimento della superficie
+   Frame3d frSurf2 ;
+   bOk = bOk && pGeomDB->GetGlobFrame( nId2, frSurf2) ;
+  // se riferimenti diversi, porto una copia della seconda nel riferimento della prima
+   const ISurfFlatRegion* pSfr2L = pSfr2 ;
+   PtrOwner<ISurfFlatRegion>pTmp ;
+   if ( ! AreSameFrame( frSurf1, frSurf2)) {
+      pTmp.Set( CloneSurfFlatRegion( pSfr2)) ;
+      bOk = bOk && ! IsNull( pTmp) ;
+      pSfr2L = Get( pTmp) ;
+   }
+  // eseguo l'intersezione tra le due superfici
+   bOk = bOk && pSfr1->Intersect( *pSfr2L) ;
+   ExeSetModified() ;
+  // se richiesto, salvo il comando Lua equivalente
+   if ( IsCmdLog()) {
+      string sLua = "EgtSurfFrIntersect(" + ToString( nId1) + "," +
+                                            ToString( nId2) + ")" +
+                    " -- Ok=" + ToString( bOk) ;
+      LOG_INFO( GetCmdLogger(), sLua.c_str()) ;
+   }
+   return bOk ;
+}
+
 //----------------------------------------------------------------------------
 int
 ExeExtractSurfFrChunkLoops( int nId, int nChunk, int nDestGrpId, int* pnCount)
@@ -203,7 +320,7 @@ ExeExtractSurfFrChunkLoops( int nId, int nChunk, int nDestGrpId, int* pnCount)
    ExeSetModified() ;
   // se richiesto, salvo il comando Lua equivalente
    if ( IsCmdLog()) {
-      string sLua = "EgtExtractSurfFrChunkLoops(" + ToString( nId) + ",{" +
+      string sLua = "EgtExtractSurfFrChunkLoops(" + ToString( nId) + "," +
                                                     ToString( nChunk) + "," +
                                                     ToString( nDestGrpId) + ")" +
                     " -- Id=" + ToString( nFirstId) + ",Nbr=" + ToString( nCount) ;
@@ -257,7 +374,7 @@ ExeExtractSurfTmFacetLoops( int nId, int nFacet, int nDestGrpId, int* pnCount)
    ExeSetModified() ;
   // se richiesto, salvo il comando Lua equivalente
    if ( IsCmdLog()) {
-      string sLua = "EgtExtractSurfTmFacetLoops(" + ToString( nId) + ",{" +
+      string sLua = "EgtExtractSurfTmFacetLoops(" + ToString( nId) + "," +
                                                     ToString( nFacet) + "," +
                                                     ToString( nDestGrpId) + ")" +
                     " -- Id1=" + ToString( nFirstId) + ",Nbr=" + ToString( nCount) ;
diff --git a/EXE_Nesting.cpp b/EXE_Nesting.cpp
index c7233c2..c6593c9 100644
--- a/EXE_Nesting.cpp
+++ b/EXE_Nesting.cpp
@@ -242,7 +242,7 @@ CreateFlatPartsByRegions( int nLay)
         // conservo solo le parti interne
          for ( int k = 0 ; k < int( ccClass.size()) ; ++ k) {
             if ( ccClass[k].nClass != CRVC_IN)
-               inCrv.Remove( ccClass[k].dParS, ccClass[k].dParE) ;
+               inCrv.Subtract( ccClass[k].dParS, ccClass[k].dParE) ;
          }
         // tratti di curva rimasti
          int nNum = inCrv.GetCount() ;
@@ -410,7 +410,7 @@ VerifyAndAdjustFlatParts( void)
            // conservo solo le parti interne
             for ( int k = 0 ; k < int( ccClass.size()) ; ++ k) {
                if ( ccClass[k].nClass != CRVC_IN)
-                  inCrv.Remove( ccClass[k].dParS, ccClass[k].dParE) ;
+                  inCrv.Subtract( ccClass[k].dParS, ccClass[k].dParE) ;
             }
          }
         // tratti di curva rimasti
diff --git a/EgtExecutor.rc b/EgtExecutor.rc
index e663075..36a1933 100644
Binary files a/EgtExecutor.rc and b/EgtExecutor.rc differ
diff --git a/LUA_GdbModifySurf.cpp b/LUA_GdbModifySurf.cpp
index 92a5f4d..76f7623 100644
--- a/LUA_GdbModifySurf.cpp
+++ b/LUA_GdbModifySurf.cpp
@@ -56,6 +56,54 @@ LuaExplodeSurf( lua_State* L)
    return 2 ;
 }
 
+//-------------------------------------------------------------------------------
+static int
+LuaSurfFrAdd( lua_State* L)
+{
+  // 2 parametro : Id1, Id2
+   int nId1 ;
+   LuaCheckParam( L, 1, nId1)
+   int nId2 ;
+   LuaCheckParam( L, 2, nId2)
+   LuaClearStack( L) ;
+  // unisco alla prima regione la seconda
+   bool bOk = ExeSurfFrAdd( nId1, nId2) ;
+   LuaSetParam( L, bOk) ;
+   return 1 ;
+}
+
+//-------------------------------------------------------------------------------
+static int
+LuaSurfFrSubtract( lua_State* L)
+{
+  // 2 parametro : Id1, Id2
+   int nId1 ;
+   LuaCheckParam( L, 1, nId1)
+   int nId2 ;
+   LuaCheckParam( L, 2, nId2)
+   LuaClearStack( L) ;
+  // sottraggo dalla prima regione la seconda
+   bool bOk = ExeSurfFrSubtract( nId1, nId2) ;
+   LuaSetParam( L, bOk) ;
+   return 1 ;
+}
+
+//-------------------------------------------------------------------------------
+static int
+LuaSurfFrIntersect( lua_State* L)
+{
+  // 2 parametro : Id1, Id2
+   int nId1 ;
+   LuaCheckParam( L, 1, nId1)
+   int nId2 ;
+   LuaCheckParam( L, 2, nId2)
+   LuaClearStack( L) ;
+  // interseco la prima regione con la seconda
+   bool bOk = ExeSurfFrIntersect( nId1, nId2) ;
+   LuaSetParam( L, bOk) ;
+   return 1 ;
+}
+
 //----------------------------------------------------------------------------
 static int
 LuaExtractSurfFrChunkLoops( lua_State* L)
@@ -111,6 +159,9 @@ LuaInstallGdbModifySurf( LuaMgr& luaMgr)
    bool bOk = ( &luaMgr != nullptr) ;
    bOk = bOk && luaMgr.RegisterFunction( "EgtInvertSurf", LuaInvertSurf) ;
    bOk = bOk && luaMgr.RegisterFunction( "EgtExplodeSurf", LuaExplodeSurf) ;
+   bOk = bOk && luaMgr.RegisterFunction( "EgtSurfFrAdd", LuaSurfFrAdd) ;
+   bOk = bOk && luaMgr.RegisterFunction( "EgtSurfFrSubtract", LuaSurfFrSubtract) ;
+   bOk = bOk && luaMgr.RegisterFunction( "EgtSurfFrIntersect", LuaSurfFrIntersect) ;
    bOk = bOk && luaMgr.RegisterFunction( "EgtExtractSurfFrChunkLoops", LuaExtractSurfFrChunkLoops) ;
    bOk = bOk && luaMgr.RegisterFunction( "EgtExtractSurfTmFacetLoops", LuaExtractSurfTmFacetLoops) ;
    return bOk ;