英国夜火车DAYTIME SERVICES.

Customers can continue to use valid daytime train tickets on the Caledonian Sleeper on the West Highland Line between Glasgow Queen Street and Fort William (both directions),
请问什么是有效的白天票呢?
https://www.sleeper.scot/timetables/daytime-services
我可以在格拉斯哥上夜火车坐硬座去威廉堡么?谢谢