It is a Hashtag used on twitter by railway enthusiasts to write about night trains that have a dining car attached.
“Caledonian Sleeper” is the collective name for night train services between London and Scotland, dining car included.
The “Dacia” is a famous long-distance night train between Bucharest, Romania, Budapest, Hungary and Vienna, Austria.
The “Night Riviera” is a night train operated by GWR between London Paddington and Penzance.
“Nightjet” is a brand name given by Austrian railway company ÖBB to its overnight passenger train services.
The Vygruppen (VY) is a government-owned railway company which operates passenger train services in Norway and Sweden. Their dining cars are called “VY Café”.
Since 1948 WARS’ area of business is the provision of accommodation and hospitality services for PKP.