Writes the DXF data of this object. 

This function is called by dxfOut() to allow the object to write its data. 

When overriding this function: 1) Call assertReadEnabled(). 2) Call the parent class's dxfOutFields(pFiler). 3) Use pFiler to call the OdDbDxfFiler methods to write each of the object's data items in the order they were written.