It is just in the name - no direct transfer from flight to train assumed - is really just a cheap roundtrip ticket from wherever to wherever, but believe it has to be purchased before arrival in Switzerland (you then just assign the destinations and dates as you feel free) - link here:

http://www.raileurope.com/rail-ticke...d-pricing.html

The first class option for only $66 more (than 2nd class) return for what would be at a minimum 6:28 to Zermatt and back seems a great deal.