POSDAO describes the validator selection method for the xDai Stable Chain. We are currently in phase 1, and planning to transition to phase 2 in Q4, 2020.
Phase 1: Permissioned POSDAO, where selected validators place xDai STAKE into the protocol and receive rewards in return for their participation (signing blocks, producing random numbers and malicious behavior reporting). Validators sign blocks in a prescribed order, using the AuRa consensus process.
Phase 2: Public POSDAO, where validators are selected based on the amount of STAKE they place into the protocol along with an on-chain RNG. The validator set will be capped at 19, and validator candidates will need to place a minimums of 20K STAKE and setup a valid node to be eligible for participation. In addition, public delegators will be able to place STAKE on candidates, increasing their chances of becoming validators in the next set. The validator set will have the opportunity to change weekly.