Only for timings. If your ticket is otherwise valid for travel, but just not on that particular train, the barriers will operate. There’sca limit to the info that a mag strip on a paper ticket can carry.
But a
QR▸ code, which seems to be replacing the magnetic strip, can carry far more. Whether it is used in this way I don't know but I'm sure the potential is there if it should be wanted in the future.
Over here, in the recent major refurbishment of Rennes station, all the ticket barriers were converted to scan QR codes, which are printed on all of our tickets.
Rennes is our Brittany rail network's flagship station - being the regional capital - and currently the only one of our stations to feature ticket barriers. We are still very much advocates of the "open stations" approach, with controls coming far more from the requirement to validate tickets in the on-platform "composter" machines before travel, along with frequent on board ticket checks.
As I've said elsewhere on the forum though, you can be expect to be very quickly challenged at a staffed station if you attempt to enter without a mask.