I got Trenitalia webpage and wrote my journey details and they give me some solution containing some regional trains with bold or red letters for journey.E.g: 12:15 rome TE(first) RO OST(red letter) RM TRAS(red letter) from rome to pisa in the same box from rome to pisa. Whats that? Should I change my train in the red ones or they are stops to collect people for same train?
So complex for me Italia train webpage: My IQ is not enough for it :)) I think regional tickets doesnt offer seat guarantee, who comes first, seats first??