On Ymir, Key Day is when someone officially comes of age. For Ymirborn, this is on the 21st anniversay of their official birthday. For any Awakened who were under 21 when they entered the Starseed, an anniversary day was calculated for an official Ymir birthday. Starting age 21, each birthday they will get a government-mandated day off.
When someone becomes 21, they are recognised as adults by Ymir law. Part of that is that they receive a key to their Universal Basic Income housing, which is a small self-sufficient apartment. This apartment contains several tools and housewares that the person can then use and bring with them to wherever they want to live. Their UBI apartment remains their personal property until death, though trading it in is allowed if properly motivated.
Ymirborn Birthdays
For privacy purposes, the exact birthdate of Ymirborn is kept classified, requiring Security Clearance Level 4. This is mainly so that family cannot be easily determined, since a known birthdate could be used to find any family that celebrated a birth. Instead, Ymirborn receive a random saturday from their birth month as their official birthday. This means there are only 50 birthday celebration moments on Ymir, one per week.
Earthborn Anniversary Days
For those born on earth, their age is known from when they went into cryosleep. The remaining time until their next birthday, was then converted into the artificial 25h days of Ymir society, and added to their Awakening Day to reason what their converted birthday would be. The first saturday on/after that birthday, is their Anniversary Day and counts as their official Ymir birthday.
The government gives you a day off on your birthday, also government forces your birthday to be on Saturday. hmm. :P I'd like to know why it is unsecure for people to know family connections? Maybe you could elaborate somewhere/sometime why all the security levels are in place. what prompted the people on Ymir to be so private?
Let's see if the gold prompts cover that. =) Short summary is that they don't want anyone to be blackmailable, so to prevent abuse of data, they help obscure family connections within all official documents. They are paranoid against themselves, so there's a lot of protection protocols in place against abuse of power. Needless to say, some are claiming 'we just need to ditch that', and others immediately mentally go 'okay so you can't be trusted, check'.
Too low they build who build beneath the stars - Edward Young