function validate_required(field)
{
  with (field)
  {
    if (value==null||value=="") {return false;}
    else {return true}
  }
}

function validate_form(thisform)
{
  with (thisform)
    {
    if ((validate_required(LastName)==true) && (validate_required(CaseSeq)==true)){
      if (CaseSeq.value == "001234"){
        CaseSeq.value = '';
        return true;
      } else {
        alert("Please enter a case number OR a last name, but not both.");
        LastName.focus();return false;
      }
    } else {
      if  ((validate_required(LastName)==false) && (validate_required(CaseSeq)==false)){
        alert("Please enter a case number OR a last name to search.");
        LastName.focus();return false;
      } else {
        return true;
      }
    }
  }
}