After a rising edge at input set S, the output Q is activated. The state remains stored until S is no longer active and input reset R is triggered. The input S is dominant – so that if only S is off and R on is the output Q is disabled.
There is also a trigger input Tr. This allows the output Q to be switched on and off with a rising edge input. For this input to work both S and R need to be off.
The block can be set to be retentive, this is done by clicking on the battery symbol to set the red NOT dot on the block (input is by default inactive).