VARCHAR(n) to VARCHAR(m) where m > n — always safe, instant. - CHAR(n) to CHAR(m) where m > n — safe but triggers REORG PENDING on z/OS because existing rows must be padded to the new length. - DECIMAL(p,s) to DECIMAL(p2,s) where p2 > p (same scale, wider precision) — safe on both platforms. - SMALL