diff --git a/EGkSurfBezier.h b/EGkSurfBezier.h
index 3ed53c8..d53d306 100644
--- a/EGkSurfBezier.h
+++ b/EGkSurfBezier.h
@@ -18,6 +18,7 @@
 
 class PolyLine ;
 class ICurveComposite ;
+class ISurfFlatRegion ;
 class ISurfTriMesh ;
 
 //----------------------------------------------------------------------------
@@ -35,6 +36,7 @@ class __declspec( novtable) ISurfBezier : public ISurf
       virtual bool SetControlPoint( int nInd, const Point3d& ptCtrl) = 0 ;
       virtual bool SetControlPoint( int nIndU, int nIndV, const Point3d& ptCtrl, double dW) = 0 ;
       virtual bool SetControlPoint( int nInd, const Point3d& ptCtrl, double dW) = 0 ;
+      virtual bool SetTrimRegion( const ISurfFlatRegion& sfrTrimReg) = 0 ;
       virtual bool GetInfo( int& nDegU, int& nDegV, int& nSpanU, int& nSpanV, bool& bIsRat, bool& bTrimmed) const = 0 ;
       virtual const Point3d& GetControlPoint( int nIndU, int nIndV, bool* pbOk) const = 0 ;
       virtual const Point3d& GetControlPoint( int nInd, bool* pbOk) const = 0 ;
@@ -57,6 +59,9 @@ class __declspec( novtable) ISurfBezier : public ISurf
       virtual const ISurfTriMesh* GetAuxSurf( void) const = 0 ;
 } ;
 
+//-----------------------------------------------------------------------------
+static const double SBZ_TREG_COEFF = 1000 ;
+
 //-----------------------------------------------------------------------------
 inline ISurfBezier* CreateSurfBezier( void)
                { return (static_cast<ISurfBezier*>( CreateGeoObj( SRF_BEZIER))) ; }