diff --git a/EGkSurfTriMesh.h b/EGkSurfTriMesh.h
index 2cd362b..4e65b08 100644
--- a/EGkSurfTriMesh.h
+++ b/EGkSurfTriMesh.h
@@ -138,6 +138,7 @@ class __declspec( novtable) ISurfTriMesh : public ISurf
       virtual bool GetPartLoops( int nPart, POLYLINEVECTOR& vPL) const = 0 ;
       virtual bool RemovePart( int nPart) = 0 ;
       virtual ISurfTriMesh* ClonePart( int nPart) const = 0 ;
+      virtual bool GetPartAndShellFromFacet( int nFacet, int& nPart, int& nShell) const = 0 ;
       virtual bool SetTFlag( int nId, int nTFlag) = 0 ;
       virtual bool GetTFlag( int nId, int& nFlag) const = 0 ;
       virtual int  GetMaxTFlag( void) const = 0 ;
diff --git a/EXeExecutor.h b/EXeExecutor.h
index ae31689..9cdf698 100644
--- a/EXeExecutor.h
+++ b/EXeExecutor.h
@@ -813,6 +813,7 @@ EXE_EXPORT int  ExeSurfFrGetZigZagInfill( int nId, int nDestGrpId, double dStep,
 EXE_EXPORT int  ExeSurfTmVertexCount( int nId) ;
 EXE_EXPORT int  ExeSurfTmFacetCount( int nId) ;
 EXE_EXPORT int  ExeSurfTmPartCount( int nId) ;
+EXE_EXPOR  bool ExeSurfTmGetPartAndShellFromFacet( int nSurfTm, int nFacet, int& nPart, int& nShell) const = 0 ;
 EXE_EXPORT bool ExeSurfTmGetVertex( int nId, int nVert, int nRefId, Point3d& ptVert) ;
 EXE_EXPORT bool ExeSurfTmGetNearestVertex( int nId, const Point3d& ptNear, int nRefId, int& nVert, Point3d& ptVert) ;
 EXE_EXPORT bool ExeSurfTmTriangleNormVersor( int nId, int nTria, int nRefId, Vector3d& vtNorm) ;