er is going to infinity. 
    Those background values affect the fd forward result of the model.<br>
</td></tr></table>
<table><tr><td>
    <a name="para"></a>PARA MODEL: In this model type, the length 
      and width can differ for different layers corresponding to different resolution 
      properties. In the dialog the number of layers, the layer boundaries and 
      its resistivities can be changed the same way like for grid model.
    The lower left boundary of the model is depicted by x0 and y0. By