With Ferret as the backend, we can visualize or list data in its native form, or to regrid it to a fixed-z axis. In the xml for the dataset, we need to add two things:

1. A Ferret property pointing to the thickness variable <thk_var>, and if it's in a separate dataset, the dataset containing that variable, <thk_url>
   
2. A UI element so that the constraint is available to regrid curvilinear to rectilinear data. An example UI file is in Example_hybrid_Z_ui.xml
   

   <properties>
      <ferret>
         <thk_url>http://someplace.edu/thredds/dodsC/lthk</thk_url>
         <thk_var>lthk</thk_var>
      </ferret>
      <ui>
         <default>file:ui.xml#Example_hybrid_Z</default>
      </ui>
   </properties>

    <menus>
        <menu type="constraint" name="Hybrid_ZText">
          <item values="Native_Z_section">Z slices in Native Z Coordinates</item>
        </menu>
         <menu type="constraint" name="Hybrid_ZOps">
            <item values="=">=</item> 
        </menu>
        <menu type="constraint" name="Hybrid_ZVal">
            <item values="yes">yes</item>
            <item values="no">no</item>
        </menu> 
    </menus>