Terminology

Date: 2026-04-22

This project uses target as the canonical package term for the variable being forecast.

Target Versus Y

Use target in public package language:

• recipe keys and manifest fields;

• registry axis names and descriptions;

• docs and examples;

• artifact column descriptions;

• extension protocol prose.

Use y only when it is clearly local mathematical notation or a short internal array variable next to X, such as model.fit(X, y) style estimator code. When docs discuss papers that write Y_t or y_{t+h}, introduce it as paper notation and then return to target.

Context	Preferred term
Public API	target, targets, target_transformer
Registry	horizon_target_construction, target_transform, target_missing_policy
Manifest/docs	target series, target scale, target level
Local numerical code	X_train, y_train is acceptable
Paper formulas	Y_t or y_{t+h} only after explicitly marking it as notation

Current Compatibility Names

Some older artifact columns and values still contain y:

• y_true, y_pred, y_true_level, y_pred_level, y_pred_model_scale;

• legacy horizon_target_construction=future_target_level_t_plus_h.

Keep these accepted for backward compatibility. New docs and generated recipes should prefer canonical target-language values such as future_target_level_t_plus_h. Future artifact migrations should add target aliases before removing any y_* columns.