function yes(z){
  document.getElementById(z+1).disabled=false;
  document.getElementById(z+2).disabled=false;
  document.getElementById(z+3).disabled=false;
}

function no(z){
  document.getElementById(z+1).checked=false;
  document.getElementById(z+2).checked=false;
  document.getElementById(z+3).checked=false;
  document.getElementById(z+1).disabled=true;
  document.getElementById(z+2).disabled=true;
  document.getElementById(z+3).disabled=true;
}

function validateForm(myForm) {

  if(""==myForm.fname.value) {
  alert("Please enter your first name.");
  return false;
  }

  if(""==myForm.lname.value) {
  alert("Please enter your last name.");
  return false;
  }

  if(""==myForm.suffix.value) {
  alert("Please select a suffix entry.");
  return false;
  }

  if(""==myForm.company.value) {
  alert("Please enter a company or practice name.");
  return false;
  }

  if(""==myForm.addr1.value) {
  alert("Please enter an address.");
  return false;
  }

  if(""==myForm.city.value) {
  alert("Please enter a city.");
  return false;
  }

  if(""==myForm.zip.value) {
  alert("Please enter a zip code.");
  return false;
  }

  if(""==myForm.phone.value) {
  alert("Please enter your phone number.");
  return false;
  }
  
  if(""==myForm.fee.value && ""==myForm.hotel.value) {
  alert("Please choose either a registration day or hotel reservation");
  return false;  
  }
  
  if((myForm.day1.disabled==false && myForm.day2.disabled==false && myForm.day3.disabled==false) &&
     (myForm.day1.checked==false && myForm.day2.checked==false && myForm.day3.checked==false)) {
  alert("You must select at least one day.");
  return false;
  }

  if(""==myForm.emailAddr.value) {
  alert("Please enter your email address.");
  return false;
  }
  
  if (myForm.emailAddr.value.length > 0) {
    if (!(/^\w+([\.-]?\w+)*@\w+([\.-]?\w+)*(\.\w{2,3})+$/.test(myForm.emailAddr.value))){
      alert("Invalid E-mail Address! Please re-enter.")
      return (false)
    }
    
  }
}