A bit obscure.......but you never know with this exam.
IFRIC make Agenda Decisions. They tend to be on very technical matters and compliance is voluntary. Examples on link below. Don't worry - you don't need to learn them!
https://cdn.ifrs.org/-/media/feature/supporting-implementation/agenda-decisions/agenda-decision-compilations/agenda-decision-compilation-volume-1.pdf?la=en
The point is that, when agenda decisions are made, companies may choose to change accounting policy - this can be very expensive because they would have to restate prior year / do prior year adjustment.
So, the ED proposes that there will be no need to restate prior year / do prior period afjustment if COST OUTWEIGHS BENEFIT. Any changes would be adjusted PROSPECTIVELY.
Even if it doesn't come up in the exam, you can dine out on that snippet of knowledge.