function validate_email(field, alerttxt)
{
	with (field)
	{
		apos = value.indexOf("@");
		dotpos = value.lastIndexOf(".");
		if (apos<1 || dotpos-apos<2)
		{
			if (alerttxt != "") alert(alerttxt);
			return false;
		}
		else
		{
			return true;
		}
	}
}
function validate_combo(field, alerttxt)
{
	if (field.selectedIndex == 0)
	{
		alert(alerttxt);
		return false;
	}
	return true;
}
function validate_empty(field, alerttxt)
{
	if (field.value == "")
	{
		alert(alerttxt);
		return false;
	}
	return true;
}
function validate_numeric(field, alerttxt)
{
	var valid = "0123456789";
	for (var i = 0; i<field.value.length; i++)
	{
		temp = ""+field.value.substring(i, i+1);
		if (valid.indexOf(temp) == "-1")
		{
			alert(alerttxt);
			return false;
		}
	}
	return true;
}
function validate_numberlength(field, alerttxt, length)
{
	if (field.value.length < length)
	{
		alert(alerttxt);
		return false;
	}
	return true;
}
function validate_select(field, alerttxt)
{
	alert(field.selectedIndex);
	if (field.selectedIndex == 0)
    {
        alert(alerttxt);
		return false;
    }
	return true;
}
function validate_form(thisform)
{
	with (thisform)
	{
		if (validate_empty(namesurname, "Please enter your name and surname!") == false)
		{
			namesurname.focus();
			return false;
		}
		else if (validate_empty(tel, "Please enter your mobile number!") == false)
		{
			tel.focus();
			return false;
		}
		else if (validate_numeric(tel, "Please enter only numbers to mobile field!") == false)
		{
			tel.focus();
			return false;
		}
		else if (validate_email(mail, "Please enter a valid e-mail address!") == false)
		{
			mail.focus();
			return false;
		}
		else if (validate_combo(flightarrival, "Please select a country!") == false)
		{
			flightarrival.focus();
			return false;
		}
		else if (validate_empty(reservation, "Please enter your reservation number!") == false)
		{
			flightcode.focus();
			return false;
		}
		else if (validate_empty(transferdate, "Please enter your transfer date!") == false)
		{
			transferdate.focus();
			return false;
		}
		else if (validate_empty(flightarrivaltime, "Please enter your flight arrival time code!") == false)
		{
			flightarrivaltime.focus();
			return false;
		}
		else if (validate_empty(flightcode, "Please enter your flight code!") == false)
		{
			flightcode.focus();
			return false;
		}
	}
}