The 63 A rating at 35 °C is the baseline; the breaker must be derated as ambient temperature rises — 59.16 A at 40 °C, 57.14 A at 45 °C, 55.06 A at 50 °C, 52.92 A at 55 °C, and 50.65 A at 60 °C. B-curve (trips at 3–5× In) is standard for resistive and general-purpose loads — lighting, control transformers, small heaters. It avoids nuisance trips from inrush on motor circuits; for motor-starting duty, a C-curve would be more typical, but B-curve is correct for the listed railway and mechanical-engineering applications. The 2-pole form (2P) isolates both phase and neutral in single-phase AC circuits.
The combined terminal at top and bottom accepts conductors without separate busbar links.