function __checkValue(el, fieldName)
    {
        if (el.value == '')
        {
            alert('Field ' + fieldName + ' cannot be empty!');
            el.focus();
            return false;
        }
        else
        {
            return true;
        }
    }
    
    function __checkSelect(el, fieldName)
    {
        if (el.value == '')
        {
            alert('You must select ' + fieldName);
            el.focus();
            return false;
        }
        else
        {
            return true;
        }
    }
    
    function __checkEmail(el, fieldName)
    {
       reg = new RegExp("[0-9a-z_]+([-+.][0-9a-z_]+)*@[0-9a-z_]+([-.][0-9a-z_]+)*\.[0-9a-z_]+([-.][0-9a-z_]+)*", 'i');
       if(!reg.test(el.value))
       {
            alert('Field ' + fieldName + ' must be in a valid email format, e.g. name@domain.com');       
            el.focus();
            return false;
       }
       else
       {
            return true;
       }
    }