Variables

Each variable has a validated Identifier, a VariableRole, and an optional Unit. The available roles are State, Control, and Observed. A world constructor requires laws only for State; a simulation request can supply values only for non-state controls.

Use Observed for columns retained in a world’s expression namespace without treating them as integrated state. Discovery builds state roles from the configured state columns and marks remaining dataset columns as controls.

Roles document execution rules. They do not encode measurement noise, latent variables, distributions, or causal status.