function checkFields() {
missinginfo = "";

if (document.form.CustomerName.value == "") {
missinginfo += "\n  -  Your name";
}
if (document.form.CustomerInstitution.value == "") {
missinginfo += "\n  -  Institution";
}
if (document.form.CustomerDepartment.value == "") {
missinginfo += "\n  -  Department";
}
if (document.form.CustomerAddress.value == "") {
missinginfo += "\n  -  Address";
}
if (document.form.CustomerCity.value == "") {
missinginfo += "\n  -  City";
}
if (document.form.CustomerState.value == "") {
missinginfo += "\n  -  State";
}
if (document.form.CustomerZip.value == "") {
missinginfo += "\n  -  Zip";
}
if (document.form.CustomerPhone.value == "") {
missinginfo += "\n  -  Phone";
}
if (document.form.CustomerCardNumber.value == "") {
missinginfo += "\n  -  Credit card number";
}
if (document.form.Title.value == "") {
missinginfo += "\n  -  Title";
}
if (document.form.Author.value == "") {
missinginfo += "\n  -  Author";
}
if (document.form.CourseName.value == "") {
missinginfo += "\n  -  Course name";
}
if (document.form.CourseNumber.value == "") {
missinginfo += "\n  -  Course number";
}
if (document.form.CourseEnrollment.value == "") {
missinginfo += "\n  -  Course enrollment";
}
if (document.form.CourseStartDate.value == "") {
missinginfo += "\n  -  Course start date";
}
if ((document.form.CustomerEmail.value == "") || 
(document.form.CustomerEmail.value.indexOf('@') == -1) || 
(document.form.CustomerEmail.value.indexOf('.') == -1)) {
missinginfo += "\n  -  Email \(needs an \"@\" or \".\"\)";
}
if (missinginfo != "") {
missinginfo ="_______________________________\n" +
"Please correctly fill in these fields:\n" +
missinginfo + "\n_______________________________" +
"\nPlease re-enter and submit again.";
alert(missinginfo);
return false;
}
else return true;
}