diff --git a/EXE_GdbCreateSurf.cpp b/EXE_GdbCreateSurf.cpp
index 7c2cf3a..9bda430 100644
--- a/EXE_GdbCreateSurf.cpp
+++ b/EXE_GdbCreateSurf.cpp
@@ -1444,14 +1444,14 @@ ExeCreateSurfTmByVolZmap( int nParentId, int nZmapId, int nPart)
 
 //-------------------------------------------------------------------------------
 int
-ExeCreateSurfBezier( int nParentId, int nDegU, int nDegV, const PNTVECTOR& vPnt, int nRefType)
+ExeCreateSurfBezier( int nParentId, int nDegU, int nDegV, int nSpanU, int nSpanV, const PNTVECTOR& vPnt, int nRefType)
 {
    IGeomDB* pGeomDB = GetCurrGeomDB() ;
    VERIFY_GEOMDB( pGeomDB, GDB_ID_NULL)
    nParentId = AdjustId( nParentId) ;
    bool bOk = true ;
-  // il numero dei punti deve essere pari al prodotto dei gradi + 1
-   int nDim = ( nDegU + 1) * ( nDegV + 1) ;
+  // il numero dei punti deve essere pari al prodotto dei gradi per gli span + 1
+   int nDim = ( nDegU * nSpanU + 1) * ( nDegV * nSpanV + 1) ;
    bOk = bOk && ( vPnt.size() == nDim) ;
   // recupero il riferimento di immersione della superficie
    Frame3d frLoc ;
@@ -1460,7 +1460,7 @@ ExeCreateSurfBezier( int nParentId, int nDegU, int nDegV, const PNTVECTOR& vPnt,
    PtrOwner<ISurfBezier> pSurfBez( CreateSurfBezier()) ;
    bOk = bOk && ! IsNull( pSurfBez) ;
   // inizializzo la superficie di Bezier
-   bOk = bOk && pSurfBez->Init( nDegU, nDegV, false) ;
+   bOk = bOk && pSurfBez->Init( nDegU, nDegV, nSpanU, nSpanV, false) ;
   // setto i punti di controllo
    for ( int i = 0 ; i < nDim && bOk ; ++ i) {
      // eventuale trasformazione del punto nel riferimento locale
@@ -1482,7 +1482,9 @@ ExeCreateSurfBezier( int nParentId, int nDegU, int nDegV, const PNTVECTOR& vPnt,
       }
       string sLua = "EgtSurfBezier(" + IdToString( nParentId) + "," +
                                        ToString( nDegU) + "," +
-                                       ToString( nDegV) + ",{" +
+                                       ToString( nDegV) + "," +
+                                       ToString( nSpanU) + "," +
+                                       ToString( nSpanV) + ",{" +
                                        sPC + "}," +
                                        RefTypeToString( nRefType) + ")" +
                     " -- Id=" + ToString( nId) ;
@@ -1494,14 +1496,14 @@ ExeCreateSurfBezier( int nParentId, int nDegU, int nDegV, const PNTVECTOR& vPnt,
 
 //-------------------------------------------------------------------------------
 int
-ExeCreateSurfBezierRational( int nParentId, int nDegU, int nDegV, const PNTUVECTOR& vPntW, int nRefType)
+ExeCreateSurfBezierRational( int nParentId, int nDegU, int nDegV, int nSpanU, int nSpanV, const PNTUVECTOR& vPntW, int nRefType)
 {
    IGeomDB* pGeomDB = GetCurrGeomDB() ;
    VERIFY_GEOMDB( pGeomDB, GDB_ID_NULL)
    nParentId = AdjustId( nParentId) ;
    bool bOk = true ;
-  // il numero dei punti deve essere pari al prodotto dei gradi + 1
-   int nDim = ( nDegU + 1) * ( nDegV + 1) ;
+  // il numero dei punti deve essere pari al prodotto dei gradi per gli span + 1
+   int nDim = ( nDegU * nSpanU + 1) * ( nDegV * nSpanV + 1) ;
    bOk = bOk && ( vPntW.size() == nDim) ;
   // recupero il riferimento di immersione della superficie
    Frame3d frLoc ;
@@ -1510,7 +1512,7 @@ ExeCreateSurfBezierRational( int nParentId, int nDegU, int nDegV, const PNTUVECT
    PtrOwner<ISurfBezier> pSurfBez( CreateSurfBezier()) ;
    bOk = bOk && ! IsNull( pSurfBez) ;
   // inizializzo la superficie di Bezier
-   bOk = bOk && pSurfBez->Init( nDegU, nDegV, true) ;
+   bOk = bOk && pSurfBez->Init( nDegU, nDegV, nSpanU, nSpanV, true) ;
   // setto i punti di controllo
    for ( int i = 0 ; i < nDim && bOk ; ++ i) {
      // eventuale trasformazione del punto nel riferimento locale
@@ -1532,7 +1534,9 @@ ExeCreateSurfBezierRational( int nParentId, int nDegU, int nDegV, const PNTUVECT
       }
       string sLua = "EgtSurfBezierRat(" + IdToString( nParentId) + "," +
                                           ToString( nDegU) + "," +
-                                          ToString( nDegV) + ",{" +
+                                          ToString( nDegV) + "," +
+                                          ToString( nSpanU) + "," +
+                                          ToString( nSpanV) + ",{" +
                                           sPC + "}," +
                                           RefTypeToString( nRefType) + ")" +
                     " -- Id=" + ToString( nId) ;
diff --git a/EXE_GdbGetSurf.cpp b/EXE_GdbGetSurf.cpp
index 17c8ae1..096db76 100644
--- a/EXE_GdbGetSurf.cpp
+++ b/EXE_GdbGetSurf.cpp
@@ -874,7 +874,7 @@ ExeSurfBezierGetPoint( int nSurfId, double dU, double dV, int nRefId, Point3d& p
    const ISurfBezier* pSbz = GetSurfBezier( pGeomDB->GetGeoObj( nSurfId)) ;
    bool bOk = ( pSbz != nullptr) ;
   // richiedo il punto
-   bOk = bOk && pSbz->GetPointD1D2( dU, dV, ptP) ;
+   bOk = bOk && pSbz->GetPointD1D2( dU, dV, ISurfBezier::FROM_MINUS, ISurfBezier::FROM_MINUS, ptP) ;
   // gestione trasformazioni ( eventuali)
    bOk = bOk && TransformPoint( pGeomDB, nSurfId, nRefId, ptP) ;
   // se richiesto, salvo il comando Lua equivalente
@@ -892,15 +892,19 @@ ExeSurfBezierGetPoint( int nSurfId, double dU, double dV, int nRefId, Point3d& p
 
 //----------------------------------------------------------------------------
 bool
-ExeSurfBezierGetPointD1( int nSurfId, double dU, double dV, int nRefId, Point3d& ptP, Vector3d& vtDerU, Vector3d& vtDerV)
+ExeSurfBezierGetPointD1( int nSurfId, double dU, double dV, int nUsd, int nVsd, int nRefId,
+                         Point3d& ptP, Vector3d& vtDerU, Vector3d& vtDerV)
 {
    IGeomDB* pGeomDB = GetCurrGeomDB() ;
    VERIFY_GEOMDB( pGeomDB, GDB_ID_NULL)
   // recupero la superficie di Bezier
    const ISurfBezier* pSbz = GetSurfBezier( pGeomDB->GetGeoObj( nSurfId)) ;
    bool bOk = ( pSbz != nullptr) ;
+  // direzioni di approccio
+   ISurfBezier::Side nSbzUsd = ( nUsd > 0 ? ISurfBezier::FROM_PLUS : ISurfBezier::FROM_MINUS) ;
+   ISurfBezier::Side nSbzVsd = ( nVsd > 0 ? ISurfBezier::FROM_PLUS : ISurfBezier::FROM_MINUS) ;
   // richiedo il punto
-   bOk = bOk && pSbz->GetPointD1D2( dU, dV, ptP, &vtDerU, &vtDerV) ;
+   bOk = bOk && pSbz->GetPointD1D2( dU, dV, nSbzUsd, nSbzVsd, ptP, &vtDerU, &vtDerV) ;
   // gestione trasformazioni ( eventuali)
    bOk = bOk && TransformPoint( pGeomDB, nSurfId, nRefId, ptP) &&
                 TransformVector( pGeomDB, nSurfId, nRefId, vtDerU) &&
@@ -922,15 +926,19 @@ ExeSurfBezierGetPointD1( int nSurfId, double dU, double dV, int nRefId, Point3d&
 
 //----------------------------------------------------------------------------
 bool
-ExeSurfBezierGetPointNrmD1( int nSurfId, double dU, double dV, int nRefId, Point3d& ptP, Vector3d& vtN, Vector3d& vtDerU, Vector3d& vtDerV)
+ExeSurfBezierGetPointNrmD1( int nSurfId, double dU, double dV, int nUsd, int nVsd, int nRefId,
+                            Point3d& ptP, Vector3d& vtN, Vector3d& vtDerU, Vector3d& vtDerV)
 {
    IGeomDB* pGeomDB = GetCurrGeomDB() ;
    VERIFY_GEOMDB( pGeomDB, GDB_ID_NULL)
   // recupero la superficie di Bezier
    const ISurfBezier* pSbz = GetSurfBezier( pGeomDB->GetGeoObj( nSurfId)) ;
    bool bOk = ( pSbz != nullptr) ;
+  // direzioni di approccio
+   ISurfBezier::Side nSbzUsd = ( nUsd > 0 ? ISurfBezier::FROM_PLUS : ISurfBezier::FROM_MINUS) ;
+   ISurfBezier::Side nSbzVsd = ( nVsd > 0 ? ISurfBezier::FROM_PLUS : ISurfBezier::FROM_MINUS) ;
   // richiedo il punto
-   bOk = bOk && pSbz->GetPointNrmD1D2( dU, dV, ptP, vtN, &vtDerU, &vtDerV) ;
+   bOk = bOk && pSbz->GetPointNrmD1D2( dU, dV, nSbzUsd, nSbzVsd, ptP, vtN, &vtDerU, &vtDerV) ;
   // gestione trasformazioni ( eventuali)
    bOk = bOk && TransformPoint( pGeomDB, nSurfId, nRefId, ptP) &&
                 TransformVector( pGeomDB, nSurfId, nRefId, vtN) &&
@@ -971,7 +979,7 @@ MySurfBezierGetCurveUV( int nSurfId, bool bIsU, double dPar, int nDestGrpId)
    if ( ! pGeomDB->GetGroupGlobFrame( nDestGrpId, frDest))
       return GDB_ID_NULL ;
   // richiedo la curva
-   PtrOwner<ICurveBezier> pCrv( bIsU ? pSbz->GetCurveOnU( dPar) : pSbz->GetCurveOnV( dPar)) ;
+   PtrOwner<ICurveComposite> pCrv( bIsU ? pSbz->GetCurveOnU( dPar) : pSbz->GetCurveOnV( dPar)) ;
    if ( IsNull( pCrv))
       return GDB_ID_NULL ;
   // se è una curva
@@ -986,7 +994,7 @@ MySurfBezierGetCurveUV( int nSurfId, bool bIsU, double dPar, int nDestGrpId)
    }
   // altrimenti è collassata in un punto
    else {
-      Point3d ptP = pCrv->GetControlPoint( 0) ;
+      Point3d ptP ; pCrv->GetStartPoint( ptP) ;
       PtrOwner<IGeoPoint3d> pGeoPnt( CreateGeoPoint3d()) ;
       if ( IsNull( pGeoPnt)  ||  ! pGeoPnt->Set( ptP))
          return GDB_ID_NULL ;
@@ -1040,7 +1048,7 @@ ExeSurfBezierGetCurveV( int nSurfId, double dU, int nDestGrpId)
 
 //----------------------------------------------------------------------------
 bool
-ExeSurfBezierGetInfo( int nSurfId, int& nDegU, int& nDegV, bool& bIsRat, bool& bTrimmed)
+ExeSurfBezierGetInfo( int nSurfId, int& nDegU, int& nDegV, int& nSpanU, int& nSpanV, bool& bIsRat, bool& bTrimmed)
 {
    IGeomDB* pGeomDB = GetCurrGeomDB() ;
    VERIFY_GEOMDB( pGeomDB, GDB_ID_NULL)
@@ -1048,12 +1056,14 @@ ExeSurfBezierGetInfo( int nSurfId, int& nDegU, int& nDegV, bool& bIsRat, bool& b
    const ISurfBezier* pSbz = GetSurfBezier( pGeomDB->GetGeoObj( nSurfId)) ;
    bool bOk = ( pSbz != nullptr) ;
   // recupero le info (gradi in U e V, flag di razionale)
-   bOk = bOk && pSbz->GetInfo( nDegU, nDegV, bIsRat, bTrimmed) ;
+   bOk = bOk && pSbz->GetInfo( nDegU, nDegV, nSpanU, nSpanV, bIsRat, bTrimmed) ;
   // se richiesto, salvo il comando Lua equivalente
    if ( IsCmdLog()) {
       string sLua = "EgtSurfBezierGetInfo(" + ToString( nSurfId) + ")" +
                     " -- DegU=" + ( bOk ? ToString( nDegU) : "nil") +
                     " -- DegV=" + ( bOk ? ToString( nDegV) : "nil") +
+                    " -- SpanU=" + ( bOk ? ToString( nSpanU) : "nil") +
+                    " -- SpanV=" + ( bOk ? ToString( nSpanV) : "nil") +
                     " -- IsRat=" + ( bOk ? ToString( bIsRat) : "nil") +
                     " -- Trim=" + ( bOk ? ToString( bTrimmed) : "nil") ;
       LOG_INFO( GetCmdLogger(), sLua.c_str()) ;
diff --git a/EXE_GeoSnap.cpp b/EXE_GeoSnap.cpp
index 800caa4..f6b7bd7 100644
--- a/EXE_GeoSnap.cpp
+++ b/EXE_GeoSnap.cpp
@@ -457,12 +457,10 @@ ExeAtParamVector( int nId, double dU, int nSide, int nRefId, Vector3d& vtV)
      // recupero la curva
       const ICurve* pCrv = GetCurve( pGObj) ;
      // assegno il lato di approccio
-      ICurve::Side nSide = ICurve::FROM_MINUS ;
-      if ( nSide > 0)
-         nSide = ICurve::FROM_PLUS ;
+      ICurve::Side nCrvSide = ( nSide > 0 ? ICurve::FROM_PLUS : ICurve::FROM_MINUS) ;
      // recupero la direzione
       Point3d ptP ;
-      if ( ! pCrv->GetPointTang( dU, nSide, ptP, vtV))
+      if ( ! pCrv->GetPointTang( dU, nCrvSide, ptP, vtV))
          return false ;
    }
    else
diff --git a/EgtExecutor.rc b/EgtExecutor.rc
index 61bca47..9273558 100644
Binary files a/EgtExecutor.rc and b/EgtExecutor.rc differ
diff --git a/LUA_GdbCreateSurf.cpp b/LUA_GdbCreateSurf.cpp
index d959d49..4e29eab 100644
--- a/LUA_GdbCreateSurf.cpp
+++ b/LUA_GdbCreateSurf.cpp
@@ -700,20 +700,28 @@ LuaCreateSurfTmByVolZmap( lua_State* L)
 static int
 LuaCreateSurfBezier( lua_State* L)
 {
-  // 4 o 5 parametri : ParentId, DegreeU, DegreeV, CtrlPnts [, nRefType]
+  // da 4 a 7 parametri : ParentId, DegreeU, DegreeV [, SpanU, SpanV], CtrlPnts [, nRefType]
    int nParentId ;
    LuaCheckParam( L, 1, nParentId)
    int nDegU ;
    LuaCheckParam( L, 2, nDegU)
    int nDegV ;
    LuaCheckParam( L, 3, nDegV)
+   int nSpanU = 1, nSpanV = 1 ;
    PNTVECTOR vPnt ;
-   LuaCheckParam( L, 4, vPnt)
    int nRefType = RTY_DEFAULT ;
-   LuaGetParam( L, 5, nRefType) ;
+   if ( LuaGetParam( L, 4, nSpanU)) {
+      LuaCheckParam( L, 5, nSpanV)
+      LuaCheckParam( L, 6, vPnt)
+      LuaGetParam( L, 7, nRefType) ;
+   }
+   else {
+      LuaCheckParam( L, 4, vPnt)
+      LuaGetParam( L, 5, nRefType) ;
+   }
    LuaClearStack( L) ;
   // creo la superficie
-   int nId = ExeCreateSurfBezier( nParentId, nDegU, nDegV, vPnt, nRefType) ;
+   int nId = ExeCreateSurfBezier( nParentId, nDegU, nDegV, nSpanU, nSpanV, vPnt, nRefType) ;
   // restituisco il risultato
    if ( nId != GDB_ID_NULL)
       LuaSetParam( L, nId) ;
@@ -726,20 +734,28 @@ LuaCreateSurfBezier( lua_State* L)
 static int
 LuaCreateSurfBezierRational( lua_State* L)
 {
-  // 4 o 5 parametri : ParentId, DegreeU, DegreeV, CtrlPntWs [, nRefType]
+  // da 4 a 7 parametri : ParentId, DegreeU, DegreeV [, SpanU, SpanV], CtrlPntWs [, nRefType]
    int nParentId ;
    LuaCheckParam( L, 1, nParentId)
    int nDegU ;
    LuaCheckParam( L, 2, nDegU)
    int nDegV ;
    LuaCheckParam( L, 3, nDegV)
+   int nSpanU = 1, nSpanV = 1 ;
    PNTUVECTOR vPntW ;
-   LuaCheckParam( L, 4, vPntW)
    int nRefType = RTY_DEFAULT ;
-   LuaGetParam( L, 5, nRefType) ;
+   if ( LuaGetParam( L, 4, nSpanU)) {
+      LuaCheckParam( L, 5, nSpanV)
+      LuaCheckParam( L, 6, vPntW)
+      LuaGetParam( L, 7, nRefType) ;
+   }
+   else {
+      LuaCheckParam( L, 4, vPntW)
+      LuaGetParam( L, 5, nRefType) ;
+   }
    LuaClearStack( L) ;
   // creo la superficie
-   int nId = ExeCreateSurfBezierRational( nParentId, nDegU, nDegV, vPntW, nRefType) ;
+   int nId = ExeCreateSurfBezierRational( nParentId, nDegU, nDegV, nSpanU, nSpanV, vPntW, nRefType) ;
   // restituisco il risultato
    if ( nId != GDB_ID_NULL)
       LuaSetParam( L, nId) ;
diff --git a/LUA_GdbGetSurf.cpp b/LUA_GdbGetSurf.cpp
index 708f934..6fae536 100644
--- a/LUA_GdbGetSurf.cpp
+++ b/LUA_GdbGetSurf.cpp
@@ -673,20 +673,24 @@ LuaSurfBezierGetPoint( lua_State* L)
 static int
 LuaSurfBezierGetPointD1( lua_State* L)
 {
-  // 3 o 4 parametri : nSurfId, dU, dV [, nRefId]
+  // 5 o 6 parametri : nSurfId, dU, dV, nUsd, nVsd [, nRefId]
    int nSurfId ;
    LuaCheckParam( L, 1, nSurfId)
    double dU ;
    LuaCheckParam( L, 2, dU)
    double dV ;
    LuaCheckParam( L, 3, dV)
+   int nUsd ;
+   LuaCheckParam( L, 4, nUsd)
+   int nVsd ;
+   LuaCheckParam( L, 5, nVsd)
    int nRefId = nSurfId ;
-   LuaGetParam( L, 4, nRefId) ;
+   LuaGetParam( L, 6, nRefId) ;
    LuaClearStack( L) ;
   // recupero i dati del punto
    Point3d ptP ;
    Vector3d vtDerU, vtDerV ;
-   bool bOk = ExeSurfBezierGetPointD1( nSurfId, dU, dV, nRefId, ptP, vtDerU, vtDerV) ;
+   bool bOk = ExeSurfBezierGetPointD1( nSurfId, dU, dV, nUsd, nVsd, nRefId, ptP, vtDerU, vtDerV) ;
    if ( bOk) {
       LuaSetParam( L, ptP) ;
       LuaSetParam( L, vtDerU) ;
@@ -704,21 +708,25 @@ LuaSurfBezierGetPointD1( lua_State* L)
 static int
 LuaSurfBezierGetPointNrmD1( lua_State* L)
 {
-  // 3 o 4 parametri : nSurfId, dU, dV [, nRefId]
+  // 5 o 6 parametri : nSurfId, dU, dV, nUsd, nVsd [, nRefId]
    int nSurfId ;
    LuaCheckParam( L, 1, nSurfId)
    double dU ;
    LuaCheckParam( L, 2, dU)
    double dV ;
    LuaCheckParam( L, 3, dV)
+   int nUsd ;
+   LuaCheckParam( L, 4, nUsd)
+   int nVsd ;
+   LuaCheckParam( L, 5, nVsd)
    int nRefId = nSurfId ;
-   LuaGetParam( L, 4, nRefId) ;
+   LuaGetParam( L, 6, nRefId) ;
    LuaClearStack( L) ;
   // recupero i dati del punto
    Point3d ptP ;
    Vector3d vtN ;
    Vector3d vtDerU, vtDerV ;
-   bool bOk = ExeSurfBezierGetPointNrmD1( nSurfId, dU, dV, nRefId, ptP, vtN, vtDerU, vtDerV) ;
+   bool bOk = ExeSurfBezierGetPointNrmD1( nSurfId, dU, dV, nUsd, nVsd, nRefId, ptP, vtN, vtDerU, vtDerV) ;
    if ( bOk) {
       LuaSetParam( L, ptP) ;
       LuaSetParam( L, vtN) ;
@@ -786,11 +794,14 @@ LuaSurfBezierGetInfo( lua_State* L)
    LuaClearStack( L) ;
   // recupero la curva
    int nDegU, nDegV ;
+   int nSpanU, nSpanV ;
    bool bIsRat, bTrimmed ;
-   bool bOk = ExeSurfBezierGetInfo( nSurfId, nDegU, nDegV, bIsRat, bTrimmed) ;
+   bool bOk = ExeSurfBezierGetInfo( nSurfId, nDegU, nDegV, nSpanU, nSpanV, bIsRat, bTrimmed) ;
    if ( bOk) {
       LuaSetParam( L, nDegU) ;
       LuaSetParam( L, nDegV) ;
+      LuaSetParam( L, nSpanU) ;
+      LuaSetParam( L, nSpanV) ;
       LuaSetParam( L, bIsRat) ;
       LuaSetParam( L, bTrimmed) ;
    }
@@ -799,8 +810,10 @@ LuaSurfBezierGetInfo( lua_State* L)
       LuaSetParam( L) ;
       LuaSetParam( L) ;
       LuaSetParam( L) ;
+      LuaSetParam( L) ;
+      LuaSetParam( L) ;
    }
-   return 3 ;
+   return 6 ;
 }
 
 //----------------------------------------------------------------------------
diff --git a/LUA_GeoSnap.cpp b/LUA_GeoSnap.cpp
index 8b7460d..7b39ae3 100644
--- a/LUA_GeoSnap.cpp
+++ b/LUA_GeoSnap.cpp
@@ -239,7 +239,7 @@ LuaMidVector( lua_State* L)
 static int
 LuaAtParamVector( lua_State* L)
 {
-  // 2, 3 o 4 parametri : Id, U, nSide [, nRefId]
+  // 3 o 4 parametri : Id, U, nSide [, nRefId]
    int nId ;
    LuaCheckParam( L, 1, nId)
    double dU ;