function check_commentform() {
	if (!document.getElementById) { return true; }

	var md5_input = document.getElementById("ai_md5");
	var code_input = document.getElementById("code");
	var salt_input = document.getElementById("ai_salt");
	var name_input = document.getElementById("author");
	var email_input = document.getElementById("email");
	var text_input = document.getElementById("comment");
	var alertbox = document.getElementById("commentalert");
	
	if (!md5_input) { return true; }
	if (!code_input) { return true; }
	if (!salt_input) { return true; }
	if (!name_input) { return true; }
	if (!email_input) { return true; }
	if (!text_input) { return true; }
	if (!alertbox) { return true; }

	var code = code_input.value;
	var salt = salt_input.value;
	var name = name_input.value;
	var email = email_input.value;
	var text = text_input.value;

	if (name.length == 0) {
		alertbox.innerHTML = "Name is required.";
		alertbox.style.display = 'block';
		return false;
	}
/*	if (email.length == 0) {
		alertbox.innerHTML = "E-mail is required. Please note that it will not be made visible.";
		alertbox.style.display = 'block';
		return false;
	} */
	if (text.length == 0) {
		alertbox.innerHTML = "Please write the comment.";
		alertbox.style.display = 'block';
		return false;
	}
	if (hex_md5(code.toUpperCase() + salt) != md5_input.value) {
		alertbox.innerHTML = "The authentication code does not match. Please check that it is typed correctly. You can also reload the page to get a new code, if the current is difficult to read.";
		alertbox.style.display = 'block';	
		return false;
	}

	return true;
}