What do Icu and Ics refer to on the label of a Powerpact breaker?

How to interpret ICU and ICS on a Powerpact Breaker

Molded Case Circuit Breaker

Icu indicates the ultimate interrupt current the breaker can withstand, but may not be able to be put back in service. Ics indicates the interrupt current the breaker can withstand and still be put back in service.