     <li>&nbsp; <a href="field3d.htm">FIELD3D</a>&nbsp;&nbsp; Computes
        field for a three-dimensionally varying SSP using adiabatic mode
        theory.</li>
    </ul>
    <h2>Group IV: Plotting Routines that use Group III Program Output:</h2>
    <ul style="font-family: monospace;">
      <li>&nbsp; PLOTSHD&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Plots tranmission
        loss in plan or elevation, i.e. an (x,y) plot or an (r,z) plot.</li>
      <li>&nbsp; PLOTRAYXY&nbsp;&nbsp;&nbsp; Plots the ray paths of th