Which translates to NGK B6S:
B = 14mm plug
6 = heat rating
none = 11.2mm thread depth
S = Copper core

I should explain, after the heat rating number you can only have E, H, L & EH, the appearance of an S means the default for thread depth applies depending on the first letter as A, B/BM or G.

The same as a B6L where L defines 11.2mm thread depth, its another way of saying B6LS I suppose.

We don't see N-D plugs at all here.

R.