Also what is the "2" in ND2 all about, I can't see
any difference day and night?


It is common, now, to file for ND2 or DA-2 even though the desired mode is
actually ND1 or DA-1.

That way, if one mode proofs OK, yet the other mode doesn't, there are more
options available.

In theory, one could refile for ND1 or DA-1, but that's another Form 301,
another big check to the consultant and another big check to the communications
attorney, and ... in short ... a waste of money.

In the days before dial-a-power, ND2 made some sense for the case where a
station could, say, make 1 kW work days, but just missed 1 kW nights, and it
didn't want to refile for 1 kW-D, 0.5 kW-N.

So ... 1 kW-D and no resistor, and 1 kW-N with a resistor, simulating a less
efficient radiator, was a possibility.

Today ... 1 kW-D and 0.82 kW-N might be one possible example, for a station
with 225 degree stick, which is required to radiate no more than the Class B
minimum efficiency with 1 kW at night.

I think San Diego's ex-KDB (or was it ex-KGB ... both are historic calls in
SoCal) is operated similarly to this.