Conventionally, yes. However the discussion is whether it is worth the club selling this area at 10% lower capacity and simply having "unreserved" on the match ticket, or season ticket. There are many EFL clubs who employ this system in their away sections and whether it could be utilised to improve atmosphere in a home section. It's a system that can be used by clubs if they wish.
Rail seating and standard seating are no different in that they have lettered rows and numbered seats, they're identical in every way except with rail seating there's a bar to lean on in front of you and maybe some more legroom. How you sell tickets in those areas is what is open to debate.