A self latching relay is one where you close it by passing current through the coil, but then when you stop passing current through the coil, it stays closed. (or vice versa, ie open it).
If you want, you can add an electronic latch to the circuit, so that when the micro output stops passing current, the latch keeps passing current through the relay, so that the relay stays closed, (or stays open, whatever)............but obviously when circuit power is removed, the relay will un-latch....so this is not really a "latching relay"