diff --git a/API_GdbModifyCurve.cpp b/API_GdbModifyCurve.cpp
index 7c3bc17..5d88e58 100644
--- a/API_GdbModifyCurve.cpp
+++ b/API_GdbModifyCurve.cpp
@@ -103,6 +103,46 @@ __stdcall EgtOffsetCurve( int nId, double dDist, int nType)
    return ( bOk  ? TRUE : FALSE) ;
 }
 
+//----------------------------------------------------------------------------
+BOOL
+__stdcall EgtChangeClosedCurveStartPoint( int nId, const double ptP[3], int nRefType)
+{
+   IGeomDB* pGeomDB = GetCurrGeomDB() ;
+   VERIFY_GEOMDB( pGeomDB, FALSE)
+   bool bOk = true ;
+  // recupero la curva
+   ICurve* pCurve = GetCurve( pGeomDB->GetGeoObj( nId)) ;
+   bOk = bOk && ( pCurve != nullptr) ;
+  // recupero il riferimento locale
+   Frame3d frLoc ;
+   bOk = bOk && pGeomDB->GetGlobFrame( nId, frLoc) ;
+  // porto in locale il punto vicino ad iniziale
+   Point3d ptPL = GetPointLocal( pGeomDB, ptP, nRefType, frLoc) ;
+  // recupero la posizione parametrica della proiezione di questo punto sulla curva
+   DistPointCurve distPC( ptPL, *pCurve) ;
+   double dPar ;
+   int nFlag ;
+   bOk = bOk && distPC.GetParamAtMinDistPoint( 0, dPar, nFlag) ;
+  // cambio il punto iniziale
+   if ( bOk  &&  pCurve->GetType() == CRV_ARC)
+      bOk = bOk && dynamic_cast<ICurveArc*>(pCurve)->ChangeStartPoint(dPar) ;
+   else if ( bOk  &&  pCurve->GetType() == CRV_COMPO)
+      bOk = bOk && dynamic_cast<ICurveComposite*>(pCurve)->ChangeStartPoint(dPar) ;
+   else
+      bOk = false ;
+   EgtSetModified() ;
+  // se richiesto, salvo il comando Lua equivalente
+   if ( IsCmdLog()) {
+      string sLua = "EgtChangeClosedCurveStartPoint(" + ToString( nId) + ",{" +
+                                                        ToString( Point3d( ptP)) + "}," +
+                                                        RefTypeToString( nRefType) + ")" +
+                    " -- Ok=" + ToString( bOk) ;
+      LOG_INFO( GetCmdLogger(), sLua.c_str()) ;
+   }
+  // restituisco il risultato
+   return ( bOk ? TRUE : FALSE) ;
+}
+
 //----------------------------------------------------------------------------
 BOOL
 __stdcall EgtModifyCurveStartPoint( int nId, const double ptP[3], int nRefType)
diff --git a/EgtInterface.rc b/EgtInterface.rc
index b2f3e2c..c120f4c 100644
Binary files a/EgtInterface.rc and b/EgtInterface.rc differ
diff --git a/LUA_GdbCreateCurve.cpp b/LUA_GdbCreateCurve.cpp
index 4a49cc3..fb9f05e 100644
--- a/LUA_GdbCreateCurve.cpp
+++ b/LUA_GdbCreateCurve.cpp
@@ -406,11 +406,11 @@ LuaCreateCurveArc2PVNEx( lua_State* L)
    int nIdE ;
    LuaCheckParam( L, 5, nIdE)
    Vector3d vtDirS ;
-   LuaCheckParam( L, 4, vtDirS)
+   LuaCheckParam( L, 6, vtDirS)
    Vector3d vtNorm ;
-   LuaCheckParam( L, 5, vtNorm)
+   LuaCheckParam( L, 7, vtNorm)
    int nRefType = RTY_DEFAULT ;
-   LuaGetRefType( L, 6, nRefType) ;
+   LuaGetRefType( L, 8, nRefType) ;
    LuaClearStack( L) ;
   // creo l'arco
    int nId = EgtCreateCurveArc2PVNEx( nParentId, ptStart.v, ptEnd.v, StringToSep( sSepE), nIdE,
diff --git a/LUA_GdbModifyCurve.cpp b/LUA_GdbModifyCurve.cpp
index 2b40afd..3b088c3 100644
--- a/LUA_GdbModifyCurve.cpp
+++ b/LUA_GdbModifyCurve.cpp
@@ -63,6 +63,24 @@ LuaOffsetCurve( lua_State* L)
    return 1 ;
 }
 
+//----------------------------------------------------------------------------
+static int
+LuaChangeClosedCurveStartPoint( lua_State* L)
+{
+  // 2 o 3 parametri : Id, NewStart [, sRefType]
+   int nId ;
+   LuaCheckParam( L, 1, nId)
+   Point3d ptStart ;
+   LuaCheckParam( L, 2, ptStart)
+   int nRefType = RTY_DEFAULT ;
+   LuaGetRefType( L, 3, nRefType) ;
+   LuaClearStack( L) ;
+  // modifico il punto iniziale
+   bool bOk = ( EgtChangeClosedCurveStartPoint( nId, ptStart.v, nRefType) != FALSE) ;
+   LuaSetReturn( L, bOk) ;
+   return 1 ;
+}
+
 //----------------------------------------------------------------------------
 static int
 LuaModifyCurveStartPoint( lua_State* L)
@@ -331,6 +349,7 @@ LuaInstallGdbModifyCurve( lua_State* L)
    try {
       lua_register( L, "EgtInvertCurve", LuaInvertCurve) ;
       lua_register( L, "EgtOffsetCurve", LuaOffsetCurve) ;
+      lua_register( L, "EgtChangeClosedCurveStartPoint", LuaChangeClosedCurveStartPoint) ;
       lua_register( L, "EgtModifyCurveStartPoint", LuaModifyCurveStartPoint) ;
       lua_register( L, "EgtModifyCurveEndPoint", LuaModifyCurveEndPoint) ;
       lua_register( L, "EgtModifyCurveExtrusion", LuaModifyCurveExtrusion) ;