This set of cards is a thought experiment for creating a "standard" environment by grabbing a random set of cards from Magic's history and calling it a standard block.
Generated using:
curl https://mtgjson.com/api/v5/AtomicCards.json | jq -r '.data[] | .[] | .name' | shuf -n 1881
At ~8:00 PM EST 2023-02-13. 1881
since that was the number of standard-legal cards at the time.