1step,rule,n_before,n_after,n_removed,rationale21,drop months before 1992-03-01 (missing neworder_chg / lags unavailable; spec training start),417,415,2,TASK.md fixes training start s >= 1992-03-0132,drop months s with s+1 > last origin 2026-08-01 (target not available at last origin),415,413,2,information-availability rule: y_{s+1} must be dated <= origin4