意铁意大利至瑞士fare的问题

4月底前往意大利，然后想从意大利去瑞士。在意铁网站上尝试购买威尼斯至日内瓦的火车票，fare type有很多种，这里想问关于smart的定义。

SMART

A limited-availability ticket that can be bought up until 7 days before departure; it is non-refundable and non-modifiable.

For the Italy-Switzerland services: limited-availability ticket valid only for journeys in 2nd class, can be bought until 14 days before departure (non-refundable and non-modifiable).

这里意大利至瑞士can be bought until 14 days before departure是至少要提前14天购票，还是最多只能提前14天购票啊？这时候才发现英文学得不够好...