function hide (id)
{
  document.getElementById(id).style.cssText = "display: none";
}

function show (id)
{
  document.getElementById(id).style.cssText = "";
}
 
function update_registration_type ()
  {
    t = document.getElementById("registration_type");
    registration_type = t.options[t.selectedIndex].value;

    if (registration_type == "student")
      {
        show("student_div");
        hide("nonstudent_div");
      }
    else if (registration_type == "0")
      {
        hide("student_div");
        hide("nonstudent_div");
      }
    else
      {
        hide("student_div");
        show("nonstudent_div");
      }
  }

function update_presentation_div ()
  {
    t = document.getElementById("presentation_flag");
    presentation_flag = t.options[t.selectedIndex].value;

    if (presentation_flag == "yes") { show("presentation_div"); }
    else { hide("presentation_div"); }
  }