A calendar
One day a year spent asking forgiveness of everyone — including those who never knew they were wronged.
Paryushan, the annual Jain fasting festival, runs for the days leading up to it.
The year's pratikramana: the whole year turned back over, and everything the smaller reviews let through.
Micchami dukkadam — may all the wrong that has been done be in vain. Said to all living beings.
The year closes. Whoever keeps nothing else keeps this one.
Most apologies are for things the other person noticed. This one is built for everything else — the harm done without knowing, which is most of it. And the annual form is the stated minimum: a Jain who keeps pratikramana only once a year keeps this one.
If a Jain friend says it to you, the phrase back is the same one. Say it without listing what you think you did; the list is for you, not them.