For the VIA rail "discounted fare", is this a simple advance limited-flexibility booking category like for airlines, or is this a fare only available to particular categories such as youth, students, seniors, etc.?
I'm unsure because this answer states it's just a limited-flexibility thing, but its reference is a broken link; on the other hand, this VIA rail page on discounts specifically mentions youths, seniors, and others.
The exact category of the ticket is "upper berth - discounted fare".