Here's what it says on SBB website:
From SBB Website...
Route-specific class upgrade.
Before each journey, you can decide on the spur of the moment whether or not you want to travel in 1st class. Requirements.
Route-specific class upgrades are only valid in combination with the following 2nd class tickets or travelcards:
A (supersaver) ticket.
A Day Pass for the Half Fare Travelcard, Saver Day Pass, Municipal Saver Day Pass, Special Day Pass.
A GA Travelcard.
You must purchase the class upgrade BEFORE the actual departure of the train.
But I won't have any of those items. I will have a Swiss Travel Pass. For upgrade purposes is this the same as GA Travelcard or Half Fare Travelcard?