function show_main(selection)
	{
	div = document.getElementById(edition); div.style.display = 'none';
	div = document.getElementById(selection); div.style.display = 'block';
	edition = selection;
	}
	
function fill_div(target, selection)
	{
	document.getElementById(target).innerHTML = selection; 
	}

	
	
function verif_personal_data_Form()				/* Verify if form is correctly filled filled*/
	{
	form = document.forms['personal_data'];
	message = "";
	if(form.title.value == "Select")  	message = message + "<li>your title</li>";
	if(form.firstname.value == "")  	message = message + "<li>your firstname</li>";
	if(form.lastname.value == "")  		message = message + "<li>your lastname</li>";
	if(form.affiliation.value == "")  	message = message + "<li>your company/university</li>";
	if(form.address1.value == "")  		message = message + "<li>your address</li>";
	if(form.zipcode.value == "")  		message = message + "<li>your zipcode</li>";
	if(form.city.value == "")  			message = message + "<li>your city</li>";
	if(form.email.value == "")  		message = message + "<li>your email</li>";
	if(form.phone.value == "")  		message = message + "<li>your phone</li>";
	if(form.registration_class.value == "Select")  	message = message + "<li>your Class</li>";
	if(form.password.value == "")  		message = message + "<li>your password</li>";
			
	if(message != "")  					{message = "<p>You must provide</p></ul>" + message + "</ul>";}

	if(form.password.value != form.test.value) message = message + "<p>Your Password entries are not identical</p>";
			
	if(form.email.value != "")  		message = message + verify_email(form.email.value);
			
	if(message == "")  {return true;} else { show_alert("-" + message + "-"); return false;}
			
	}
	
function verif_msg_Form()
	{
	form = document.forms['send_message'];
	message = "";
	if(form.email.value == "")  		message = message + "<li>your email</li>";
	if(form.subject.value == "")  		message = message + "<li>a subject</li>";
	if(form.question.value == "")  		message = message + "<li>a question</li>";
				
	if(message != "")  				    message = "<p>You must provide  </p></ul>" + message + "</ul>";
				
	if(form.email.value != "")  		message = message + "<p>" + verify_email(form.email.value) + "</p>";
			
	if(message == "")  {return true;} else { show_alert(message); return false;}
	}