diff --git a/EGkExtDimension.h b/EGkExtDimension.h
index 3980439..e128de4 100644
--- a/EGkExtDimension.h
+++ b/EGkExtDimension.h
@@ -58,6 +58,7 @@ class __declspec( novtable) IExtDimension : public IGeoObj
       virtual double GetTextHeight( void) const = 0 ;
       virtual bool GetMidPoint( Point3d& ptMid) const = 0 ;
       virtual bool GetCenterPoint( Point3d& ptCen) const = 0 ;
+      virtual const std::string& GetSubType( void) const = 0 ;
       virtual bool ApproxWithLines( double dLinTol, double dAngTolDeg, POLYLINELIST& lstPL) const = 0 ;
 } ;