This refers to stage 2 of the Astral Codex Ten 2023 prediction contest ("Full Mode") to see how Manifold stacks up against predictors who may use Manifold's predictions and other markets or research.

See here for the discussion of the ACX 2022 results, where Manifold did very well, but there was no "Full Mode":
https://astralcodexten.substack.com/p/who-predicted-2022

Here is the group of markets for the questions: https://manifold.markets/group/acx-2023-prediction-contest

Resolves to the percentile placement that Manifold will have if it made a Full Mode submission at the same cutoff date (Feb. 1, 2022) as the rest of the Full Mode contestants.