in a circuit diagram of a SMPS there are symbols D1 -D8 (see annex) which I dont know.
I assume you don't really mean D1 - D8 as different types of diodes are referred to
I suspect you really mean D1,D2,D5,D6,D7,D8,D19 and an unmarked one in the top right … prob. D9
They are a twin diode pack
where the cathode of one diode is commoned with the anode of the other diode
I would have to search for a specific part number
are you sure it isn't already listed somewhere on the circuit sheet ?