Release State refers to an immutable, identifiable data state fixed for a given AI execution. The same release state always points to the same condition, which makes it the reference point for reproducing a result or comparing two of them.
Operational data keeps moving. Schemas get adjusted, field definitions change, policies are updated. Without a fixed release state, a result approved last month can return a different answer today with no way to say what changed.
This sits at a different layer from model versioning. Model versioning fixes which model ran; release state fixes the condition of the data that model read. Reproducibility needs both. Each execution records which release state it used, and differences between states are found by comparing them. CUBIG earlier called this a Release State; Syntitan now saves it as a data version, and each run records the version, settings, and evaluation conditions it used.