The latching function is due to the magnetic circuitry used in CR1F** contactors.
There are two inputs on the coil
- Input to latch the contactor (A1) and
- Input to release the contactor (E1).
On sending a pulse on A1 (1 to 2 seconds) the contactor closes and stays closed until a second pulse is sent on E1 (1 to 2 seconds) to release the contactor.
The wiring diagram attached provides more details.