德铁订票，确定了往返行程后，出现一段说明，

Your ticket Return Ticket, 1 adult, 2nd class, Hamburg - Berlin, Berlin - Hamburg

Sparpreis

Train-specific Booking. Exchange/return: EUR 15; excluded from the first day of validity



德铁订票，确定了往返行程后，出现上述说明，其中

Train-specific Booking. Exchange/return: EUR 15; excluded from the first day of validity

是什么意思阿？


求解～～